The impulse wave is a universally existent hazard induced by landslides nearby water basins.Predicting the characteristics of the impulse waves is of great importance for risk assessment of landslide generated waves.Previous studies often focused on the instant wave pa-rameters and selected several landslides parameters such as thickness and velocity to build predictive models for wave characteristics such as height and amplitude.The time series relations between landslide parameters and wave parameters need to be determined.This paper gives insights into the time series variation of the wave characteristics.Experiments are first conducted by using granular particles,and a time se-ries panel database is built by using experimental data.Then a time series prediction model is established for wave characteristics based on a random coefficient panel data model,and the model is tested with the support of experimental data.The proposed model provides a temporal predictive method,which compensates for the deficiency of conventional models that can only predict the instantaneous wave parameters.
The water environment in rural areas is not only an important source of water for rural residents,but also closely related to agricul-tural production,sustainable development of rural economy,and farmers'health.How to improve the water environment in rural areas has become an urgent and important issue to be solved.This paper integrates exogenous incentives theory and organizational trust theory into a unified analysis framework,using 962 household survey data from provinces such as Jiangsu,Anhui,and Shaanxi.Using the Double-hurdle model,the impact of exogenous incentives and organizational trust on farmers'willingness to participate in water environment governance is empirically analyzed,and the mediating effect of organizational trust is explored to provide a reference for promoting good governance of vil-lage water environment.The research results indicate that firstly,exogenous incentives have a significant positive impact on farmers'willing-ness and degree of participation in water environment governance.From a multidimensional perspective,both economic and emotional incen-tives have a significant positive impact on farmers'willingness and degree of participation in water environment governance.Reputation in-centives only have a significant promoting effect on willingness to participate.Secondly,organizational trust has a significant positive impact on farmers'willingness to participate in water environment governance,but it does not have a significant impact on the level of participation.From a multidimensional perspective,goodwill trust has a significant positive impact on farmers'willingness and level of participation in wa-ter environment governance.And competence trust has only a significant promoting effect on willingness to participate.Thirdly,a further mechanism analysis has found that organizational trust plays a positive mediating effect between exogenous incentives and farmers'participa-tion in water environment governance decision-making behavior.Based on the above research conclusions,this paper suggests that:firstly,village committees should improve the exogenous incentives mechanism for farmers to participate in water environment governance.The first step is to establish a credit system and punishment system for rural water environment governance,and moderately increase the performance rewards for public welfare positions such as river guards and cleaners.Then,the village committee should regularly carry out"Healthy Fami-ly"evaluation activities,actively promote exemplary models of protecting the village environment,and guide village social public opinion by utilizing farmers'emphasis on personal reputation to enhance their sense of responsibility and honor and shame in protecting the water envi-ronment.Furthermore,the village committee should actively explore the unique customs and habits of the village,regularly organize collec-tive cultural and entertainment activities to enhance the cohesion between farmers,and strengthen the relationship between the cadres and the masses to enhance farmers'sense of belonging to the village.Secondly,grassroots autonomous organizations should strive to enhance their credibility.On the one hand,grassroots governments need to regularly carry out training activities on the professional abilities of village cadres,continuously improve their office skills,and establish a talent reserve system for village cadres to strengthen the organization's talent team.On the other hand,the village committee should improve the"four discussions and two disclosures"system,standardize the proce-dures for disclosing village affairs information,safeguard the rights of farmers to know,participate,and supervise,in order to establish a fair and just image of grassroots autonomous organizations.Thirdly,the village committee should enhance farmers'subjective awareness of pub-lic affairs participation.It not only needs to fully leverage the initiative of farmers through regular organization of courtyard meetings and the establishment of opinion boxes,but also avoids the formalization of grassroots election systems,in order to ensure the political participation rights of farmers and reduce their dependence on the government.
The multi-trough aqueduct is a new type of aqueduct structure,which has the advantages of large cross section water flow,good overall workability and small deflection deformation of the channel body,but the channel body is more sensitive to uneven vertical deforma-tion.In view of the fact that this type of structure is still the first in the water conservancy industry in our country,how to establish a multi-trough aqueduct operation safety early warning monitoring index is an important problem in project operation management.At present,do-mestic scholars have put forward a number of monitoring models about aqueducts,but these models do not give clear monitoring indicators,and do not reflect the modern monitoring concept of"hierarchical monitoring,step-by-step warning".Therefore,based on the previous re-search work,this paper proposes taking the non-uniform vertical deformation at the support as the main monitoring index,and the measured value of the reinforcement at the inner wall of the trough as the secondary monitoring index,and the research results can provide a reference for the safe operation of the multi-trough aqueduct.
By using the principle of bionics,this paper treats the front,middle and rear parts of the blade working surface with hemispherical non-smooth structure,combined with the flow field CFD and acoustic field LMS for simulation calculation.The flow field and sound field re-sults of the design flow of a centrifugal pump are compared and analyzed.The results show that the non-smooth structure makes the frictional resistance of the blade smaller,and then effectively reduces the shear stress and turbulent kinetic energy on the blade surface,and the weak-ening effect is most obvious at the blade entry and exit.At the same time,the vortex strength in the impeller flow channel is significantly re-duced,and the internal vortex distribution of the pump is more uniform,which can effectively reduce its turbulent pulsation intensity as a whole,stabilize the flow field and effectively reduce the flow noise.The non-smooth structure blade can effectively reduce the total sound pressure level,among which the optimal noise reduction at the impeller outlet is 3.28 dB and the noise reduction rate is 1.9%.The total sound pressure level at the diaphragm is reduced by 3.11 dB,and the noise reduction rate is 1.82%.In summary,non-smooth blades have a good noise reduction effect compared with smooth blades,and the overall noise reduction rate is about 0.81%～1.90%.
In order to explore the evolution of hydrological cycle in the agro-pastoral ecotone under changing environment,this paper takes Mu Us Sandy Land as the study area,and data of geological,hydrological,meteorological,and applies artificial water withdrawal to estab-lish a surface(Water and Energy transfer Processes in Large river basin,WEP-L)-groundwater(Visual Modular Finite Difference Ground-water Flow,Visual-MODFLOW)joint model,the model parameters are calibrated and verified by using the monthly surface runoff data of Baijiachuan hydrological station and groundwater table data.The results show that the NSE of the monthly runoff simulation of the WEP-L model calibration and verification period is above 0.40,the R2 is above 0.65,and the relative error is within±15%,the model is relatively accurate in simulating the monthly surface runoff process in the dry season at Baijiachuan Hydrological Station.Meanwhile,the R2 of ground-water table simulated and measured during the simulation period of four representative wells in the study area simulated by the Visual MOD-FLOW model is basically above 0.58,the MAE is less than 0.3m and the RMSE is between 0.028～0.265m,suggesting that the established surface water-groundwater model can be used for distributed simulation of hydrological cycle process in the Mu Us Sandy Land.On this ba-sis,the spatial distribution characteristics of surface water-groundwater in Mu Us Sandy Land are further explored.The results show that the surface runoff and groundwater table in different regions of the Mu Us Sandy Land are significantly different,and the groundwater table is low in places with large surface runoff.From 2019 to 2020,the runoff in the Mu Us Sandy Land decreased,but the spatial distribution was basi-cally the same,showing a gradual increase from the west to the east,and the runoff in the southeast corner of the area was the largest.The groundwater table in the area remained almost unchanged from 2019 to 2020,showing that the amount of groundwater recharge and extrac-tion are basically the same.In terms of space,the difference in groundwater table in the adjacent areas of the southeast and northeast corners of the sandy land is relatively large,and the water table drops faster,which is similar to the topographical change.The research results can provide scientific support for agricultural water allocation in the agro-pastoral ecotone,and for the regional water resources planning and management.
The Additional Mass Method(AMM)has been gradually applied in the study of compaction quality testing techniques for rockfill because of its efficient,accurate and non-destructive characteristics.In this paper,the test parameters and the accuracy of different inver-sion models of the additional mass method for testing the compacted density of rockfill are investigated,and the optimized test parameters for testing the density of rockfill are obtained.Firstly,the stiffness correlation model(SCM),phase angular frequency correlation model(FCM)and digital template model(DTM)are established at the test site according to two inversion methods,namely correlation method and contour method,and then the application effect of each inversion model is evaluated at the rockfill dam compacting construction site.With the experi-ment,the model samples are expanded,and the sample mean errors and inversion relative errors before and after the expansion are analyzed.The results show that the additional mass method has a promising application in rockfill dam compacted density testing,the optimized field test parameters are highly feasible in application,the inversion results of all three models meet the accuracy requirements,among which DTM has the best application in rockfill density testing of panel rockfill dams in the Wuyue Pumping and Storage Project,and the inversion accuracy of the dry density of rockfill compaction is the highest.
Common in the inherently curved river channel,the bridge pier built toward the construction will alter the trend of the water flow movement downstream and negatively impact the stability of the embankment.The hydropower model in the Mike Zero series software is used to numerically simulate the conditions of various construction locations for the cylindrical bridge pier and the pier and the river channel in or-der to investigate the effects of diagonal bridge pier in the continuous curve,and analyze the impact of bridge piers on water level and flow ve-locity under various operating conditions.Research indicates when a bridge pier with different oblique angles at different positions in the cor-ner,the height of the maximum water in front of each pier is increasing at the bridge pier diagonal cross-intersecting angle α ranging from 30° to 60°.Additionally,the offset of the oblique pier increases the plane flow velocity of each operating state,and the flow velocity around the bridge pier increases with the size of the bridge pier's cross section.After the construction of a pier in the central area of the bridge pier,both the horizontal and vertical flow velocities along the longitudinal side of the pier decrease.The decrease in flow rate with the increase in the angle of the bridge pier becomes more evident.However,it is worth mentioning that the horizontal longitudinal rate at the back of the cor-nering coast and the back of the bumpy area increases to varying degrees,and it consistently remains higher than the flow rate prior to the construction of the pier.The influence of the water flow between adjacent curves has a reverse suppression effect on the development of the lateral circulation structure of the front curve.When the bridge connection section is built in the corner connection section,the loop of the back surface of the pier is smaller than the circulation of the bridge pier in the curve section.These findings have a basis for the design of the river bridge and shore protection engineering.
With the rapid development of industry and agriculture,river water pollution problems are becoming more and more serious.The phenomenon of water flow confluence is common in river systems.Due to the complex hydraulic characteristics of the intersection,the influx of highly concentrated pollutants from branch channels can accumulate in the downstream of the main channel,causing river water pollution and seriously threatening the water safety of downstream regions.Aiming at the water quality pollution of the confluence caused by tributary discharge,a two-dimensional hydrodynamic and water quality coupling model of the 90° equal-width open channel confluence is established based on the hydrodynamic and water quality model software Delft3D.The model parameters are calibrated through comparison and verifica-tion with physical model experiments in existing studies.The study proposes that the engineering measures of arranging submerged dams near the open channel intersection can intensify the convection of the flow,enhance the mixing of pollutants and reduce the concentration of pol-lutants,so as to solve the problem of water pollution near river confluences.A total of 14 arrangements of different submerged dam locations,lengths,and heights are numerically simulated.Then the pollutant distribution maps and flow field distribution maps under each working con-dition has been obtained,and the variation coefficient and extreme value of pollutant concentration in each section are calculated for analy-sis.The research findings show that the arrangement of submerged dams near the confluence can accelerate the mixing of pollutants,thereby reducing the extreme value of pollutant concentration.The main mechanism for the submerged dams to accelerate the mixing and diffusion of pollutants is that the transverse velocity zone and recirculation zone generated by the submerged dam intensify the flow convection effect,pro-moting the mixing of pollutants.The arrangement of submerged dams on the right bank of the main channel downstream of the confluence has a better effect on reducing the concentration of pollutants than the arrangement of submerged dams on the left bank.Among the simulated con-ditions,pollutant concentration can be most significantly reduced when the length of the submerged dam is one-half the width of the river.The higher the submerged dam,the better the effect of reducing the extreme value of pollutant concentration.The coefficient of pollutant con-centration variation can be reduced by 46%,and the maximum pollutant concentration value can be reduced by 33%under the appropriate submerged dam arrangement condition compared to the baseline condition without submerged dams.When the submerged dam is arranged across the river width,the generated transverse flow velocity area is located on the bank,which has limited effects on the mixing of pollut-ants.The research conclusions can provide a scientific basis for pollution control in converging rivers.
Aiming at the problem that the early warning method based on risk matrix and considering settlement rules is affected by massive cooperative operation data,which leads to poor early warning effect,the risk early warning of man-machine cooperative operation of the hy-dropower station under deep data fusion is proposed.The closed-loop mode of digitalized cooperative operation is constructed to ensure the stability of risk warning process of digitalized man-machine cooperative operation of hydropower station operation.The maximum confidence gain is calculated,and the features are normalized and combined,so as to build a full-dimensional data deep fusion model for hydropower stations to avoid data loss.Deep fusion data are obtained through sensor nodes,and multidimensional time series are established based on space-time in space and time to provide effective data support for the safe operation of field workers.Based on the results of intelligent per-ception and recognition of potential risks,a risk early-warning process for man-machine collaborative operation of hydropower stations based on deep data fusion is designed,so that workers can deal with on-site emergencies in time.The risk warning probability of this method is closer to the actual value,which indicates that the warning effect of this method is better.
There are many large rivers in China.Under the conditions of internal soil properties and external rainfall discharge,soil and water exchange occurs between soil and river flow on the bank slope,which leads to the instability and slip on the bank slope easily.Many river-bank slopes are binary riverbank structures dominated by silty sand soils,which have prominent security and stability problems.By taking part of the silty sand reaches of the Xiangjiang River as the research object,this paper uses the finite difference software FLAC3D,based on the fluid-solid coupling theory and strength reduction method,combined with the silty sand bank slope topography and soil data of the select-ed river reach,Rayno protective structure is proposed.A three-dimensional model of bank slope protection is established to study the influ-ence of Raynaud gaspe-Gabion cage structure protection on bank slope stability from the aspects of bank slope stress field,displacement field,shear strain increment and safety factor.Raynaud's pad produces a large compressive stress on the bank slope soil due to its own weight,which weakens the soil tension,but has no significant effect on the soil stress distribution.The revetment scheme has an obvious pro-tective effect on the horizontal displacement of the bank slope,the maximum displacement is reduced from 0.61 m to 0.19 m,the vertical dis-placement of slope foot is reduced from 0.17 m to 0.03 m,and the vertical settlement displacement of slope top is reduced from 0.28 m to 0.07 m.Under the protection of Rayon's pad,the range of shear strain increment of the bank slope is significantly reduced,the effective plastic strain zone is significantly less than that of the unprotected bank slope,and the maximum value of shear strain increment is also small-er than that of the unprotected bank slope,the shear stress of the soil mass is weakened,and the maximum area appears at the foot of the slope and the junction between the silty sand soil layer and the sandy mudstone basement.In this case,the safety factor of the bank slope reaches 1.549.The protective effect is obvious.The safety factor of the bank slope increases with the increase in the laying length of the Ray-on pad.When the laying length reaches the boundary between the silty sand soil layer and the clay layer,the Fs value has reached 1.549,which fully meets the protection requirements.When the laying length continues to the top,the safety factor is stable around 1.58.At this time,the protection effect has met the needs of the project.Through simulation,the protection effect of Renault pad scheme on the bank slope under extreme low water level is obvious,and the stability of the bank slope is significantly improved,indicating that the protection scheme is feasible.Moreover,the laying of Renault pads and Gabion cages is easy to operate,good anti-impact performance,long service life,and does not require regular maintenance and maintenance.The protective structure scheme is suitable for the bank slope.
The vibration attenuation characteristics have a great influence on the dynamic behavior of the shaft system of hydro-generator units.In order to accurately describe the vibration characteristics of the shaft system of hydro-generator units under hydraulic excitation,this paper deems it necessary to investigate the vibration attenuation characteristics of the shaft system.Firstly,a method of extracting hydraulic excitation feature based on PSO-VMD is proposed to analyze the vibration characteristics of hydraulic excitation.Then,the vibration trans-mission models with no bearing shaft unit and the vibration transmission model with no bearing shaft unit are established by wave finite ele-ment method.According to the models,the vibration transmission equation of the shaft system of the hydro-generator units is constructed by wave finite element method.And according to the constructed vibration transmission equations of the shaft system,the calculation method of the vibration attenuation coefficient of the shaft system is determined.Finally,the vibration attenuation characteristics of the shaft system are analyzed by an example.The research findings show that the vibration transmission model and vibration attenuation coefficient calculation method of shaft system of hydro-generator units proposed in this paper are feasible and effective,which provides a certain theoretical basis for further in-depth research on the influence of vibration attenuation characteristics on the dynamic behavior of shaft system of hydro-gener-ator units.
In order to study the law of flood migration,assess flood damage degree and grasp the response mechanism of major disaster fac-tors to flood disaster elasticity,help provide an ecological approach to urban rainstorm and flood disaster management and improve urban di-saster prevention and mitigation capacity,this paper takes the urban area of Jinan City as the research area,divides 28 catchment areas,combines the flood CADDIES model based on cellular automata theory,simulates the flood situation of different scenarios in the urban area of Jinan City by using actual storm rain patterns and design rain patterns,constructs the flood recovery capability evaluation model based on watershed scale changes,and constructs a double-iteration model with the help of data processing tools.And the paper designs four different flood scenarios under different conditions to evaluate and study the elastic results of flood disasters in the urban area of Jinan City under dif-ferent scenarios.The results show that the C1～C4 catchment areas are located in mountainous areas and other areas with higher terrain have higher resilience indices for flood disasters in various scenarios.The elasticity index of each catchment decreases with the increase in the re-turn period.The elasticity index of most catchments decreases with the increase in the rainfall duration.The greater the catchment depth threshold,the greater the flood elasticity index.The following conclusions are drawn:Through the combination of actual rain pattern and de-sign rain pattern,the flood inundation migration process at different times in Jinan City is simulated and verified by CADDIES model,which shows the law of the phenomenon of"flooding in the south and flooding in the north".The recurrence period,rainfall duration and water depth threshold are the important factors affecting the flood disaster resilience of the catchment area.The catchment area with higher eleva-tion in the southern mountainous areas has obvious regional advantages in terms of flood disaster elasticity.The closer the catchment area is to the urban area,the smaller the area of land use types such as grasslands and forests that are conducive to rainwater absorption and infiltra-tion,while the weaker the resilience of flood disasters.
Limited by the coarse spatial resolution,Gravity Recovery and Climate Experiment(GRACE)satellite data is difficult to be ap-plied in small or medium-sized areas.Therefore,based on the random forest algorithm,the monthly GRACE terrestrial water storage anoma-ly(TWSA)in central Yunnan from 2003 to 2020 had been improved from 1°×1° to 0.1°×0.1° from two scales,namely grid scale(Random Forest-Grid,RF-G)and regional scale(Random Forest-Zone,RF-Z),respectively.The downscaling results are compared with the down-scaling method based on PCRaster Global Water Balance(PCR-GLOBWB)hydrological model from the perspective of time and space to en-sure accuracy.Furthermore,the Empirical Orthogonal Function(EOF)method is used to decompose the orthogonal pattern and analyze the characteristics of the TWSA downscaling results,enabling a deeper understanding of data characteristics and influencing factors.The results show that the RF-Z model outperforms in downscaling TWSA for the central Yunnan region,with the correlation coefficient of 0.99,the Nash-Sutcliffe efficiency coefficient of 0.97,the root mean square error is 6.68mm,and the mean absolute error of 5.22mm.Notably,the downscaled results from RF-Z successfully mitigate gridding artifacts.The variance contribution rate of the first four eigenvectors of EOF de-composition is 91.73%.The first mode is"high in the southwest and low in the northeast",and its time coefficient has a significant seasonal rule.The second mode presents the distribution of"high in the northwest and low in the southeast"and the corresponding time coefficient shows an obvious decreasing trend.The third and fourth modes respectively present the distribution characteristics of"whole region type"and"high in northwest and low in southeast".In addition,there is a strong correlation between TWSA and NDVI in the driving variables.This study can provide data support and technical guarantee for water resources management and ecological environment protection in central Yunnan.
To address the insufficient consideration on water level safety requirements at flood control stations in conventional reservoir flood control operation,this study proposes an optimal flood control operation method for reservoir group coupled with water level calculation at ba-sin flood control stations.First,the station water level characteristics are analyzed through the multi-site water level and flow relationship to identify the key factors affecting the water level.The input features for water level calculation are screened according to the correlation be-tween the influencing factors and the water level.The multi-layer feed-forward back propagation neural network(BP neural network)is in-troduced to fit the complex non-linear relationship between the input features and the observed water level,to realize the accurate calcula-tion of water level at the station.Then,the safety margin index is proposed to quantify the station water level safety.With the objective of max-imizing the overall safety margin of the downstream flood control stations,the optimal flood control operation model for cascade reservoirs,coupled with BP neural network,is constructed.Finally,a hybrid optimization algorithm(DPSA-POA-PSO)is developed to solve the mod-el by combining the advantages of the Dynamic Programming Successive Approximation(DPSA),Progressive Optimization Algorithm(POA)and Particle Swarm Optimization(PSO).The results show that the water level calculation accuracy of the BP neural network is signifi-cantly improved by considering the station water level characteristics,and the flood level fitting deviation for typical floods is limited within 0.05m.Compared with the DPSA and PSO algorithms,the downstream overall safety margin from the hybrid optimization algorithm is im-proved by 0.88%and 2.58%in the joint operation of three cascade reservoirs,and is improved by 0.85%and 1.87%in the joint operation of five cascade reservoirs.Meanwhile,the derived operation schemes satisfies all the guaranteed water level requirements,which provides reli-able support for improving the basin flood control safety.
In order to study the sealing performance of P-type water seal in long-term service,this paper establishes a P-type viscoelastic fi-nite element model of water seal.The evolution of mechanical and deformation characteristics of water seal during long-term service is simu-lated and analyzed.Firstly,based on the creep experimental data of typical rubber materials,the parameters of Burgers constitutive model and standard linear solid model to describe the creep properties of rubber materials are determined by using the least squares principle.Sec-ondly,the creep experiment of rubber material is simulated in ANSYS,and the feasibility of viscoelastic simulation of water-sealed rubber material is verified by comparing the simulation results with the test results.The comparison results show that the Burgers model can more ac-curately reflect the creep phenomenon of rubber materials in the viscoelastic process than the standard linear solid model.Finally,in order to evaluate the sealing performance of the long-term service process of P-type water seals,the influence of viscoelasticity,the paper studies reservoir pressure and pre-pressure on contact stress and width of water seal by parameter analysis based on Burgers model.
A distribution flow method(DFM)and its ecological flow index(DEFI)and evaluation grade standard(DFGS)are proposed to study the ecological flow of rivers on the basis of Multi-probability density estimation.Taking the Yichang section of the Yangtze River as an example,The proposed DFM compared with traditional calculation method of hydrological ecological flow,method of flow evaluation,and calculation result of fish ecological flow,and the changes in river ecological flow satisfaction rate and ecological index score before and after variation are evaluated.Results show that the DFM considers the intra-and inter-annual variations in natural runoff,thereby reducing the in-fluence of extreme flow and uneven flow distribution during the year.The method can meet the actual runoff demand of river ecosystem,is su-perior to traditional hydrological method,and presents strong space-time applicability and certain application value.Inter-annual changes in wet,normal,and dry seasons should be considered,and the ecological flow level and ecological flow index scores higher or close to those be-fore the variation should be used as the criteria for water resources and ecological flow management.
The research on agricultural water quota is of great significance for promoting water conservation,rational allocation and utiliza-tion of water resources,and improving the effective utilization coefficient of irrigation water.Based on the work of industry water quota compi-lation in Gansu Province in 2022,this paper revises and evaluates the water quota for vegetable irrigation in typical irrigation areas in Gansu Province.On the basis of collecting and investigating the water consumption data of each typical irrigation area,the agricultural irrigation zones are re-divided according to the natural geographical and climatic conditions in Gansu Province,and the general value and advanced value of the water quota for vegetable irrigation are analyzed and calculated by empirical method,statistical analysis method and analogy method.The research shows that ① based on the precipitation isoline and drought index isoline,the agricultural irrigation zoning method is put forward,which takes geographical zoning and other factors affecting agricultural irrigation water into consideration.Gansu Province is di-vided into five agricultural zones,which is more in line with the geographical distribution and climate characteristics of Gansu Province than the current zoning,and can better reflect the differences in agricultural irrigation water use between different regions.②The water quota for different kinds of vegetables in each agricultural irrigation zone is between 27 00 and 9 300 m3/hm2.The maximum quota for onions is 3 750 to 9 300 m3/hm2,and the minimum quota for vegetables in solar greenhouse is 2 700 to 5 700 m3/hm2.The vegetable quota of agricultural irri-gation zones shows three trends:high,medium and low,most of which are located in the middle,and the trend of change is consistent with the characteristics of plant growth and agricultural water-saving.③ The water quota for vegetables in different agricultural zones varies great-ly,which is shown as increasing from the east to the west and from the south to the north.The Hexi Corridor is larger than the eastern Long-dong Plateau,and the central Longnan is larger than the southern Longnan,which basically conforms to the distribution law of precipitation isoline and the characteristics of regional farmland irrigation.④ Using the quantitative evaluation system,it is concluded that the coverage of vegetable irrigation quota in Gansu Province is"reasonable",the practicability is"strict",the rationality is"strict",and the progressive-ness is"reasonable".The revised vegetable quota standard has significantly improved in"four properties".
It is of great significance for soil erosion control and ecological environment management to study the influence of different land use patterns on runoff and sediment processes in the basin.Based on the measured monthly runoff and sediment data from 1996 to 2003,the SWAT model of Xixian watershed is established.According to the simulation results of SWAT model,the contribution rate of runoff and sedi-ment yield to the whole watershed under different land use types is calculated.Then,the runoff and sediment yield simulation data of each sub-basin of SWAT model are used as the output variables required by the random forest regression model,and the random forest regression model is used to evaluate the importance of different land use types to runoff and sediment processes.The results show that:① The SWAT model has high accuracy.The decisive coefficient R2 and Nash coefficient NSE of runoff and sediment rate in the regular and verification pe-riods are greater than 0.75,and the percentage of deviation PBIAS is-1,-5.6 and 5.1,9.6.The model is suitable for runoff and sediment simulation in Xixian watershed;② The contribution rates of land use types to runoff and sediment processes in the basin are in the order of woodland>dry land>paddy field>grassland and dry land>paddy field>grassland>woodland.③ The decisive coefficient R2 of each stage of the random forest regression model is basically greater than 0.5,and the fitting effect is better;the order of the importance of differ-ent land use types to the runoff and sediment process obtained by the random forest regression model is basically the same as the order of the contribution rate of different land use types to the runoff and sediment process calculated by the SWAT model,indicating that the SWAT model is used to calculate the contribution rate of different land use types to the runoff and sediment process.The accuracy is high.In summa-ry,the contribution rate of cultivated land to runoff and sediment in Xixian watershed is the largest.The method of this study can also be ap-plied to other watersheds to obtain the contribution rate of runoff and sediment of different land use types in different watersheds,and provide a reference for the efficient soil and water conservation in the watershed.
The synergy of water resources allocation pattern and land space pattern is the important foundation to ensure the economic and so-cial development.In order to evaluate water resources spatial balance scientifically and reasonably,this paper calculates the four dimensions comprehensive indicators of water conservation,rigid water demand,water resources development and utilization through the methods of en-tropy,water load index,Equilibrium based on theory of system of spatial balance of water resources.Based on the three zones such as Pearl River Delta,the Coastal Economic Zone and Northern Ecological Development Zone,the Dagum Gini coefficient method are used to evaluate the spatial balance of water resources in different regions of Guangdong Province.The research findings show that the spatial balance of water resources in different regions of Guangdong Province is mainly due to inter-regional differences.The water resources spatial equilibrium of the Pearl River Delta and the Coastal Economic Zone are relatively poor,the water resources allocation are mainly from the water transfer projects.The water resources spatial equilibrium of the Northern Ecological Development Zone are well balanced,and the water resources al-location is mainly based on the local water resources utilization,which can be used as water sources for other regions.The Dagum Gini coeffi-cient method can provide a reasonable description of differences within and between zones and the contribution of hypervariable density,and can be used as a means of evaluating the spatial equilibrium of water resources.It can provide a basis and direction for optimizing water resource allocation,and it can provide a forceful water security guarantee for improving the coordinated development of regional economy and society.
Within the hierarchical decision structure of reservoir pre-impoundment operations,the parameter equifinality of hydropower gen-eration leads to non-uniqueness of optimal solutions,i.e.,the"ill-posedness"of solving reservoir operation optimization problems.Under such circumstances,the realization of operation benefits is affected by whether the reservoir operator selects the refill plan in favor of flood safety,implying that not only competitive relationship but also cooperative potential exists between flood control and water conservation.In light of this,a cooperation incentive(CI)model based on the lower-level satisfaction is developed to provide a mechanism to promote the wa-ter conservation department's cooperation with the flood control department and enhance the reservoir operation benefit.Based on the frame-work of ill-posed bilevel programming,regarding the actual decision characteristics,the model described the nonlinear correlation between the cooperation willingness and the expected benefit of the water conservation department given certain flood control rule,so that the proba-bility of selecting the refill plan in favor of flood safety can be derived.The CI model is solved by using multi-swarm evolutionary particle swarm optimization algorithms.Quantitative indicators are proposed to evaluate the Pareto efficiency loss and overall goal achievement of the reservoir operation optimization under cooperation.In the Three Gorges Reservoir pre-impoundment case study,the results are compared with those of the optimistic,pessimistic,and partial cooperation models.Results show that the CI mechanism motivates the benefit conces-sion of the flood control department to increase hydropower generation and encourage the water conservation department's choice in favor of flood safety.Further,the efficiency loss in operation decisions due to competitive gaming process can be more prominently reduced.Findings also indicate that nonlinear satisfaction-expected benefit relationship can better describe the practical decision making in reservoir operation.
