Gypsum-based self-leveling mortar (GSL) is widely used in floor heating backfill and leveling systems due to its advantages of excellent dimensional stability, fast setting and hardening rate, and low carbon emissions. However, its poor thermal conductivity and water resistance are key technical issues that urgently need to be addressed. The use of thermally conductive materials (TCM) and cement is currently the main approach to address these issues, but their mechanism of action in gypsum-based self-leveling mortar is not yet clear. This study comparatively analyzed the application of ordinary Portland cement and belite-rich cement in gypsum-based self-leveling mortar, and based on this, systematically evaluated the effects of graphite powder (GP), iron oxide black (IOB), and aluminum hydroxide (AH) on the performance of self-leveling mortar. The results showed that the introduction of ordinary Portland cement or belite-rich Portland cement can improve the fluidity of the cementitious system, shorten the setting time, and increase the mechanical properties, water resistance, and thermal conductivity by changing the hydration process, but it will increase the shrinkage rate to some extent, especially for ordinary Portland cement. When thermally conductive materials are further added to the cementitious system containing belite-rich Portland cement, the changes in mortar properties mainly depend on the type of thermally conductive filler. Graphite powder and iron oxide black only play a filling and nucleation effect during the hydration process, while aluminum hydroxide can participate in the formation of hydration products by dissolving some ions under alkaline conditions.

Surface hydrologic connectivity is an important hydrologic characteristic for understanding hydrologic processes and catchment responses in depression-dominated areas. While tremendous recent interest remains focused on surface depression-induced hydrologic connectivity, few studies have illustrated the progressive development of hydro-connectedness at the watershed scale. The objective of this study is to identify and quantify threshold-controlled hydrologic connectivity behaviors for depression-dominated watersheds. We present a novel depression-oriented hydro-connectedness (HCd) characterization framework to recognize spatial distribution and topographic parameters of surface depressions and channels as well as the associated static/dynamic connections. The HCd was effectively applied to a depression-dominated watershed in North Dakota, U.S., and its unique capability was emphasized by the comparisons with other depression-oriented characterization algorithms/tools. The results provide an advanced understanding of the progressive expansion of connected areas and contributing area of the watershed outlet. The findings deliver new insights into threshold-controlled hydrologic connectivity and overland flow dynamics in depression-dominated areas, thereby facilitating water resource management and flood risk assessment, and supporting the development of depression-oriented hydrologic models for improved runoff prediction.

Soil moisture content (SMC) plays a vital role in agricultural productivity, water resource management, and ecosystem sustainability in semi-arid regions. Despite this importance, most existing machine learning models mainly rely on remote sensing data to predict the soil moisture variation in the surface soil; however, they are constrained by redundant input features and limited interpretability. To address these shortcomings, this study combines the Random Forest (RF) algorithm, Convolutional Neural Networks (CNN), and the Transformer framework to develop a hybrid RF-CNN-Transformer model. Specifically, the RF algorithm, CNN, and Transformer framework are respectively used for selecting influential features, extracting spatial patterns, and capturing long-term temporal dependencies. Applied to the Mu Us Sandy Land using data from six soil depths (5, 10, 20, 40, 70, and 87 cm), the model demonstrated high prediction accuracy and training efficiency across all layers compared to baseline models, with R2 values ranging from 0.8586 to 0.984 (mean R2 = 0.9507). Interpretability analysis revealed a shift in the controlling mechanisms of soil moisture: shallow-layer SMC is jointly influenced by meteorological conditions and groundwater level, whereas groundwater becomes the dominant factor in deeper layers. Notably, due to the extremely dry climate, precipitation has a relatively minor impact on soil moisture dynamics across all depths. Overall, the proposed RF-CNN-Transformer model enhances both the predictive capability and interpretability of soil moisture variation, supporting precision irrigation and water resource optimization in agriculture, especially in arid and semi-arid regions.

Study region: Yuxi River Basin, a typical semi-arid region between the Mu Us Sandy Land and the Loess Plateau. Study focus: In arid and semi-arid regions, limited research has addressed how hydrological processes affect irrigation demand, especially under varying evaporation and recharge conditions. This research gap constrains water resources utilization and ecosystem protection. By combining the stable isotope method with water resources assessment, this study analyzed the hydrologic characteristics and proposed a coordinated surface-groundwater irrigation strategy based on spatiotemporal dynamics of evaporation and recharge. New hydrological insights: In most areas of the Yuxi River basin, groundwater is the main source of the river, accounting for 89.24 % and 88.18 % of river recharge during dry and wet periods, respectively. Except for June, river water remains a reliable source for agricultural irrigation during the irrigation season. Reservoirs and lakes significantly influence local evaporation and surface-groundwater interactions, with distinct spatio-temporal differences in the upstream and midstream sections. Furthermore, due to the combined influence of groundwater, tributaries, evaporation, and open water bodies, there is river water recharging groundwater in areas around river confluences, lakes, and res-ervoirs, with recharge percentages reaching 90.98 % and 81.63 % during dry and wet periods, respectively. Thus, groundwater should be the preferred irrigation source in these areas during May, July, and August. This isotope-based method offers scientific guidance for sustainable irrigation management in arid and semi-arid regions.

The confined groundwater of arid sedimentary plains has been disturbed by long-term anthropogenic extraction, and its hydrochemical quality is required for sustainable development. The present research investigates the hydrochemical characteristics, formation, potential health threats, and quality suitability of the confined groundwater in the central North China Plain. Results show that the confined groundwater has a slightly alkaline nature in the study area, predominantly dominated by fresh-soft Cl-Na and HCO3-Na types. Water chemistry is governed by water-rock interactions, including dissolution of evaporites and cation exchange. Approximately 97% of the sampled confined groundwaters exceed the prescribed standard for F-. It is mainly due to geological factors such as mineral dissolution, cation exchange, and competitive adsorption of HCO3- and may also be released from compacted soils because of groundwater extraction. Enriched F- in the confined groundwater can pose an intermediate and higher non-carcinogenic risk to more than 90% of the population. It poses the greatest health threat to the population in the north-eastern part of the study area, especially to infants and children. For sustainable development, the long-term use of confined groundwater for irrigation in the area should be avoided, and attention should also be paid to the potential soil salinization and infiltration risks. In the study area, 97% of the confined groundwaters are found to be excellent or good quality for domestic purposes based on Entropy-weighted Water Quality Index. However, the non-carcinogenic health risk caused by high contents of F- cannot be ignored. Therefore, it is recommended that differential water supplies should be implemented according to the spatial heterogeneity of confined groundwater quality to ensure the scientific and rational use of groundwater resources.Practitioner Points The hydrochemistry quality of confined groundwater in an arid sedimentary plain disturbed by long-term anthropogenic extraction was investigated. The suitability of confined groundwater for multiple purposes such as irrigation and drinking were evaluated. The hydrochemical characteristics and formation mechanism of confined groundwater under the influence of multiple factors were revealed. The present research investigates the hydrochemistry quality of confined groundwater in an arid sedimentary plain, which has been disturbed by long-term anthropogenic extraction. The findings reveal the suitability for multiple purposes, hydrochemical characteristics, and formation mechanism of confined groundwater.image

Groundwater resource is crucial for the development of agriculture and urban communities in valley basins of arid and semiarid regions. This research investigated the groundwater chemistry of a typical urbanized valley basin on the Tibetan Plateau to understand the hydrochemical status, quality, and controlling mechanisms of groundwater in arid urbanized valley basins. The results show groundwater is predominantly fresh and slightly alkaline across the basin, with approximately 54.17% of HCO3-Ca type. About 12.5% and 33.33% of sampled groundwaters are with the hydrochemical facies of Cl-Mg·Ca type and Cl-Na type, respectively. Groundwater is found with the maximum TDS, NO3−, NO2−, and F− content of 3066 mg/L, 69.33 mg/L, 0.04 mg/L, and 3.12 mg/L, respectively. Groundwater quality is suitable for domestic usage at all sampling sites based on EWQI assessment but should avoid direct drinking at some sporadic sites in the urban area. The exceeding nitrogen and fluoride contaminants would pose potential health hazards to local residents, but high risks only existed for infants. Both minors and adults are at medium risk of these exceedingly toxic contaminants. Groundwater quality of predominant sites in the basin is suitable for long-term irrigation according to the single indicator of EC, SAR, %Na, RSC, KR, PI, and PS and integrated irrigation quality assessment of USSL, Wilcox, and Doneen diagram assessment. But sodium hazard, alkalinity hazard, and permeability problem should be a concern in the middle-lower stream areas. Groundwater chemistry in the basin is predominantly governed by water-rock interaction (silicate dissolution) across the basin in natural and sporadically by evaporation. Human activities have posed disturbances to groundwater chemistry and inputted nitrogen, fluoride, and salinity into groundwater. The elevated nitrogen contaminants in groundwater are from both agricultural activities and municipal sewage. While the elevated fluoride and salinity in groundwater are only associated with municipal sewage. It is imperative to address the potential anthropogenic contaminants to safeguard groundwater resources from the adverse external impacts of human settlements within these urbanized valley basins.

The Tibetan Plateau is the “Asia Water Tower” and is pivotal for Asia and the whole world. Groundwater is essential for sustainable development in its alpine regions, yet its chemical quality increasingly limits its usability. The present research examines the hydrochemical characteristics and origins of phreatic groundwater in alpine irrigation areas. The study probes the chemical signatures, quality, and regulatory mechanisms of phreatic groundwater in a representative alpine irrigation area of the Tibetan Plateau. The findings indicate that the phreatic groundwater maintains a slightly alkaline and fresh status, with pH values ranging from 7.07 to 8.06 and Total Dissolved Solids (TDS) between 300.25 and 638.38 mg/L. The hydrochemical composition of phreatic groundwater is mainly HCO3-Ca type, with a minority of HCO3-Na·Ca types, closely mirroring the profile of river water. Nitrogen contaminants, including NO3−, NO2−, and NH4+, exhibit considerable concentration fluctuations within the phreatic aquifer. Approximately 9.09% of the sampled groundwaters exceed the NO2− threshold of 0.02 mg/L, and 28.57% surpass the NH4+ limit of 0.2 mg/L for potable water standards. All sampled groundwaters are below the permissible limit of NO3− (50 mg/L). Phreatic groundwater exhibits relatively good potability, as assessed by the entropy-weighted water quality index (EWQI), with 95.24% of groundwaters having an EWQI value below 100. However, the potential health risks associated with elevated NO3− levels, rather than NO2− and NH4+, merit attention when such water is consumed by minors at certain sporadic sampling locations. Phreatic groundwater does not present sodium hazards or soil permeability damage, yet salinity hazards require attention. The hydrochemical makeup of phreatic groundwater is primarily dictated by rock–water interactions, such as silicate weathering and cation exchange reactions, with occasional influences from the dissolution of evaporites and carbonates, as well as reverse cation-exchange processes. While agricultural activities have not caused a notable rise in salinity, they are the main contributors to nitrogen pollution in the study area’s phreatic groundwater. Agricultural-derived nitrogen pollutants require vigilant monitoring to avert extensive deterioration of groundwater quality and to ensure the sustainable management of groundwater resources in alpine areas.

Study Region: Tongde Basin, a typical alpine basin on the northeastern Tibetan Plateau Study focus: Research on the hydrochemical pattern and availability of groundwater is very limited in alpine regions, which greatly hinders the rational ulitilization and scientific management of groundwater resources. Multiple approaches integrating self-organizing map, K-means, entropy weight were employed to elucidate the distinct hydrochemical evolution patterns and controlling mechanisms of groundwater in alpine basins with dense human activities. New hydrological insights for the region: Multiple hydrochemical evolution patterns were discovered for groundwater in present alpine basin on northeastern Tibetan Plateau. Groundwater presents a gradual hydrochemical evolution from the piedmont to the riverside under the natural regulation with the increasing of TDS and major ions along the flow path. While, groundwater at some sporadic sites is featured with relatively high total alkalinity due to carbonate mineral dissolution. The riverine groundwaters are regulated by the strong hydrodynamic condition of river and demonstrate fresher hydrochemical characteristics. Groundwaters in the irrigation areas are featured by elevated nitrate levels with a maximum of 42.86 mg/L, attributed to agricultural pollution inputs. A conceptual model was established to illustrate the distinct hydrochemical fingerprints, evolution patterns and controlling mechanisms of groundwater in alpine basins that with dense human activities. This research can enhance the understanding of groundwater chemical status, genesis and availability, and is beneficial for the conservation and sustainable management of groundwater resources in ecologically fragile alpine regions worldwide.

Groundwater is a critical resource for economic growth and livelihoods in the dense agricultural plains of plateaus. However, contaminations from various sources pose significant threats to groundwater quality. Understanding the sources of groundwater contamination and the mechanisms of hydrochemical control is essential for the sustainable development of agriculturally intensive plains. This research utilizes 23 datasets of groundwater chemical measurements to apply hierarchical clustering analysis, positive matrix factorization, and hydrochemical analysis techniques. Through these methods, the study identifies the sources of groundwater contamination and deciphers the hydrochemical control mechanisms within a representative intensive agricultural plain region of Yungui Plateau. The finds indicate that groundwater in the plain primarily derives from the rainfall occurred in the surrounding mountains. During the long underground flow process, groundwater undergoes water-rock interactions and ion exchanges with various lithological strata, resulting in the formation of distinct hydrochemical types. As it traverses regions influenced by human activities, groundwater encounters varying levels and types of contamination. Consequently, there is a notable variation in groundwater quality across different areas of the plain. Groundwater is dominated by the hydrochemical faces of HCO3-Ca type in the southern part of the plain. Groundwater in the piedmont region of this part exhibits the highest quality, acting as the baseline for the overall groundwater quality of the plain. Groundwater in agricultural areas of this part is severely polluted by nitrate-rich agricultural wastewater. In the central urban area, under the control of municipal wastewater discharge and denitrification, groundwater is to some extent polluted by NH4 +. In the northern sector of the plain, groundwater chemistry exhibits greater diversity due to variations in geological strata and exposure to a range of pollution sources. The majority of the regions are contaminated with SO4 2- and Cl- and present a predominance of Cl-Na type for groundwater hydrochemical facies. Groundwater at the northernmost end is polluted by NO2 -, NH4 +, and P. In addition, there is also a small amount of groundwater near the lake that is heavily polluted by fertilizers. This study provides valuable insights for the development of sound groundwater management strategies, applicable not only to the current agricultural plain but also to analogous regions worldwide. PRACTITIONER POINTS: This study probed the impact of agricultural pollution on the groundwater hydrochemistry in a cultivated plain. The research pinpointed the origins and contributions of groundwater chemicals in the cultivated agricultural plain. A conceptual model was established to illustrate groundwater chemistry formation in an intensive agricultural irrigation plain on Yungui Plateau.

Scarce rainfall and strong evaporation add complexities to estimating groundwater recharge in arid and semiarid regions. There are still many gaps in the understanding of how soil water near the ground surface interacts with the atmosphere, which increases the difficulties of determining the contribution of rainfall to groundwater in these regions. This study used a weighing lysimeter to observe the potential recharge over a 1-year period in the Mu Us Desert, northwest China. The observed data were used to explore the infiltration processes and to quantify recharge. The results show: (1) no potential recharge can be observed if the rainfall is less than 12.3 mm/day during the experimental period. The observed annual potential recharge was 29.3 mm, which accounted for 10% of the annual rainfall. (2) The threshold of soil-water content for potential recharge was determined, such that when the average soil moisture along the soil profile (0–100 cm) is larger than 0.12 cm 3 /cm 3 , the potential recharge can be observed. (3) The empirical weight function (Poisson distribution) method performed well in the estimation of recharge compared to the observed lysimeter data. In addition, the parameter γ of the Poisson distribution has a linear relationship with the average soil-water content along the soil profile. These findings can help researchers understand recharge, which has significance in groundwater resource management.

The SCS curve number (SCS-CN) method has gained widespread popularity for simulating rainfall excess in various rainfall events due to its simplicity and practicality. However, it possesses inherent structural issues that limit its performance in accurately simulating rainfall excess and infiltration over time. The objective of this study was to develop a modified CN method with temporally varying rainfall intensity (MCN-TVR) by combining a soil moisture accounting (SMA) based SCS-CN method with the SMA method in the Hydrologic Engineering Center’s Hydrologic Modeling System (HEC-HMS). In the MCN-TVR, the SMA-based SCS-CN method is utilized to simulate the cumulative rainfall excess and infiltration, while the SMA method in the HEC-HMS serves as an infiltration control function. A key advantage of the MCN-TVR is that it eliminates the need for additional input parameters by inherently linking the parameters in the two SMA-based methods. Sixteen hypothetical 24 h SCS Type II rainfall events with different soil types and five real rainfall events for the Rush River Watershed in North Dakota were used to assess the performances of the MCN-TVR method and the SMA-based SCS-CN method. In the hypothetical simulations, the rainfall excess simulated by the SMA-based SCS-CN and MCN-TVR models was compared to that simulated by a Green–Ampt model. Discrepancies were observed between the rainfall excess simulated by the SMA-based SCS-CN and Green–Ampt models, especially for coarse soils under relatively light rainfall. However, the MCN-TVR model, incorporating an infiltration control function, demonstrated its improved performance closer to the Green–Ampt model. For all the hypothetical events, the Nash–Sutcliffe efficiency (NSE) coefficient of the rainfall excess simulated by the MCN-TVR method compared to the Green–Ampt model was greater than 0.99, while the root mean standard deviation ratio (RSR) was less than 0.03. In the real applications, the SMA-based SCS-CN model failed to provide acceptable simulation of the direct runoff for rainfall events with durations of less than the time of concentration. In contrast, the MCN-TVR model successfully simulated the direct runoff for all the events with NSE values ranging from 0.65 to 0.91 and RSR values from 0.31 to 0.56.

The bipartite Turán number of a graph $H$, denoted by $ex(m,n; H)$, is the maximum number of edges in any bipartite graph $G=(X,Y; E)$ with $|X|=m$ and $|Y|=n$ which does not contain $H$ as a subgraph. In this paper, we determined $ex(m,n; F_{\ell})$ for arbitrary $\ell$ and appropriately large $n$ with comparing to $m$ and $\ell$, where $F_\ell$ is a linear forest which consists of $\ell$ vertex disjoint paths. Moreover, the extremal graphs have been characterized. Furthermore, these results are used to obtain the maximum spectral radius of bipartite graphs which does not contain $F_{\ell}$ as a subgraph and characterize all extremal graphs which attain the maximum spectral radius.

In this paper, we determine the maximum signless Laplacian spectral radius of all graphs which do not contain small books as a subgraph and characterize all extremal graphs. In addition, we give an upper bound of the signless Laplacian spectral radius of all graphs which do not contain intersecting quadrangles as a subgraph.

In recent years, market-oriented allocation of land has been promoted to support rural revitalization and urban–rural integrated development. To follow the path of sustainable development, it is necessary to improve the efficiency of resource utilization and to rationally allocate and use resources on the premise of ensuring the sustainable use of resources. This study aims to measure the degree of land marketization in Shaanxi Province, China during the period 2008–2019 and analyze its driving forces. The methods used include Gray Relation Analysis and Hot Spot Analysis. The MK trend method was used to analyze the average area of land acquired through Bidding–Listing–Auction (B-L-A), protocol, and allocation methods. The results show that the land marketization level in Shaanxi declined from 2008 to 2014 and fluctuated upwards from 2014 to 2019. In addition, B-L-A transactions increased across the province. There was little spatial heterogeneity of land marketization, but southern Shaanxi had less land marketization than the other key areas. Urbanization, non-agricultural output, and foreign direct investment were found to be the main driving factors of land marketization, while the influence of fixed asset investment and per capita disposable income declined each year. Based on these findings, we suggest that there is a need for land management reforms and urbanization efforts to encourage land marketization in southern Shaanxi. Further, we suggest that northern Shaanxi would benefit from optimizing the land use structure and focusing on the energy land market. This study also provides theoretical support for realizing the reform of the marketization of national land elements, the healthy operation of urban land marketization, and sustainable urban and rural development.

Hydrologic processes in depression-dominated areas are controlled by the spatial distribution of surface depressions and their dynamic hydrologic connectivity. Existing hydrologic models often utilize lumped ways to handle depressions, and hence their spatial features are lost in this simplification process. In this study, a unique watershed-scale, semi-distributed hydrologic model accounting for dynamic hydrologic connectivity (HYDROL-DC) is developed and the functionalities of depressions in runoff generation processes and hydrologic connectivity are respectively quantified by introducing two concepts of depression impact coefficient and connected area. Unlike other models, a new modeling framework is proposed in HYDROL-DC to facilitate separate modeling for the puddle-based units, off-stream channel-based units, and on-stream channel-based units of each subbasin. HYDROL-DC was applied to the Edmore Coulee watershed in North Dakota. The modeling results showed that depressions significantly influenced hydrologic processes and their impact capacities were mainly dominated by the storages and spatial distributions of depressions. In a subbasin with depressions of similar storage, depending on the spatial distribution of fully-filled depressions, hydrologic connectivity varied within a range. With the increase in depression storage, the variation of the range exhibited a progressive and hierarchical pattern. Additionally, depressions "blocked" the pathways of runoff water from the activated topographic units to the associated outlet in a subbasin, and such a "blocking" function became significant as more depressions were fully filled.

Topographic delineation is critical to watershed hydrologic modeling, which may significantly influence the accuracy of model simulations. In most traditional delineation methods, however, surface depressions are fully filled and hence, watershed-scale hydrologic modeling is based on depression-less topography. In reality, dynamic filling and spilling of depressions affect hydrologic connectivity and surface runoff processes, especially in depression-dominated areas. Thus, accounting for the internal hydrologic connectivity within a watershed is crucial to such hydrologic simulations. The objective of this study was to improve watershed delineation to further reveal such complex hydrologic connectivity. To achieve this objective, a new algorithm, HUD-DC, was developed for delineation of hydrologic units (HUs) associated with depressions and channels. Unlike the traditional delineation methods, HUD-DC considers both filled and unfilled conditions to identify depressions and their overflow thresholds, as well as all channels. Furthermore, HUs, which include puddle-based units and channel-based units, were identified based on depressions and channels and the detailed connectivity between the HUs was determined. A watershed in North Dakota was selected for testing HUD-DC, and Arc Hydro was also utilized to compare with HUD-DC in depression-oriented delineation. The results highlight the significance of depressions and the complexity of hydrologic connectivity. In addition, HUD-DC was utilized to evaluate the variations in topographic characteristics under different filling conditions, which provided helpful guidance for the identification of filling thresholds to effectively remove artifacts in digital elevation models.

The Horton equation has been widely used to simulate infiltration under ponding conditions and many efforts have been made to expand the applicability of this method to non-ponding conditions. However, because of the absence of appropriate drainage controls, most existing modified Horton methods cannot be used for continuous rainfall-runoff simulations with long dry time periods. The objective of this study is to develop a modified Horton infiltration model (MHI) for both event and continuous simulations with soil moisture threshold controls. Unlike other modified Horton methods, nonlinear and linear equations are used in this new method to quantify the relationships between infiltration capacity and soil water storage respectively for wet and dry soil moisture conditions (wet gravity-driven free drainage stage; dry: capillarity-dominated non-drainage stage). Two tests of the MHI model were conducted to evaluate its performance in both event and continuous simulations. Fourteen modeling scenarios were considered in the event modeling test of MHI, which involved three soil types of different initial water contents under various rainfall conditions. The simulation results of MHI were compared with those simulated by a modified Green-Amps model and the reference data from Mein and Larson (1971). Furthermore, MHI was applied to a field site in Grand Forks, North Dakota for continuous modeling and compared against the observed data, which demonstrated its capability in the modeling of infiltration and soil moisture variations.

The bowlshaped broken pieces reassembly algorithm based on the inner surface characteristics can effectively avoid the over segmentation problem caused by the fracture surface, while the difficulty lies in the accurate extraction of inner surface Therefore, an identification algorithm for inner surface of bowlshaped broken pieces based on point cloud proportion and smoothness is proposed Firstly, the surface of bowlshaped broken pieces is divided into fracture surface, bottom surface, original surface, inner surface and outer surface based on the region growing algorithm And then, according to the significant difference of point cloud proportion, the inner surface and outer surface are identified from the segmented surface group Finally, the inner surface is extracted by the smoothness value The experimental results show that this algorithm can accurately extract the inner surface of bowlshaped broken pieces and has a higher calculation speed than other algorithm

地形建模是数字地形分析的重要基础工作.实时优化适应性网格算法(ROAM算法)是目前常用的地形建模方法.但ROAM算法应用于地形可视化实时渲染时要求原始数据为正方形,且渲染后常有裂缝产生,因而该法在地形建模实践中受到较大的限制.针对ROAM算法存在的上述不足,本文提出了基于内接正方形插值方法的改进ROAM算法.通过将多边形分割为一个内接正方形和多个边缘多边形,用多边形的一个顶点依次与其他顶点相连,使边缘多边形分割为多个三角形,并根据边缘三角形面积大小,确定是否对边缘多边形进行继续分割,由此解决数据源限定为正方形的问题,利用添加拆分点的方法消除地形渲染产生的裂缝.采用不规则地形的灰度图作为高程数据源进行地形模拟实验,结果表明:改进后的ROAM算法能够消除裂缝,且对数据源无约束性要求,降低了算法复杂度,提高了整体可视化性能,能够满足地形实时动态显示的要求.

Watershed hydrologic models often possess different structures and distinct methods and require dissimilar types of inputs. As spatially-distributed data are becoming widely available, macro-scale modeling plays an increasingly important role in water resources management. However, calibration of a macro-scale grid-based model can be a challenge. The objective of this study is to improve macro-scale hydrologic modeling by joint simulation and cross-calibration of different models. A joint modeling framework was developed, which linked a grid-based hydrologic model (GHM) and the subbasin-based Soil and Water Assessment Tool (SWAT) model. Particularly, a two-step cross-calibration procedure was proposed and implemented: (1) direct calibration of the subbasin-based SWAT model using observed streamflow data; and (2) indirect calibration of the grid-based GHM through the transfer of the well-calibrated SWAT simulations to the GHM. The joint GHM-SWAT modeling framework was applied to the Red River of the North Basin (RRB). The model performance was assessed using the Nash-Sutcliffe efficiency (NSE) and percent bias (PBIAS). The results highlighted the feasibility of the proposed cross-calibration strategy in taking advantage of both model structures to analyze the spatial/temporal trends of hydrologic variables. The modeling approaches developed in this study can be applied to other basins for macro-scale climatic-hydrologic modeling.