Since 2010, Chile has been affected by a long-term drought, often referred to as the Mega-Drought. To adapt to future drought events, we need reliable hydro-climatic information based on robust observations and models. However, reliable hydro-climatic data needed for hydrological modelling of remote Andean catchments are rarely available. Our objective was therefore to identify the most suitable combination of different rainfall estimates with two rainfall-runoff models of varying complexity to reliably simulate low flows related to drought.We forced the widely used SWAT and HBV-light models with four satellite-based rainfall estimates (SREs) (CHIRPSv2, MSWEPv1.2, MSWEPv2.0, TMPA 3B42v7) and inverse distance weighted (IDW) precipitation observations for the main headwater catchment of the Imperial River basin (Araucania, 38°N). Sobol global sensitivity analysis and calibration were carried out using the hydroPSO R package, using two objective functions focused on the performance of low flows (logNSE and low flows KGE).Despite the differing amount and temporal distribution of water, for all four SREs, the Sobol sensitivity analysis resulted in robust identification of key model parameters for all SWAT optimisation runs, with most sensitivity for parameters related to deep groundwater recharge, lateral flow travel time and the SCS runoff curve number. For the HBV-light model, only parameters related to snow-melt and deep groundwater recharge were robustly identified for the wetter SRE products. For both models and the two objective functions, the best efficiencies were obtained with the wetter SREs (MSWEP v1.2 and CHIRPSv2) as well as with IDW.We found that SREs combined with rainfall-runoff modelling provide a valuable instrument to simulate daily discharges for the Upper Imperial River Basin. The resulting models are hence suitable to project low flows and water availability; information that is requested by local decision makers needed to design irrigation systems for the agricultural downstream area and the secure water supply of settlements in the context of future droughts.
The seasonally-dry tropics of northern Costa Rica are characterized by recurrent drought events with negative socio-economic impacts on a vulnerable population. Scarce hydroclimatic observational data constraints reasonable water management and often results in water scarcity issues.This study analyses hydrological drought situations using freely available Global Precipitation Products (GPP) and a Regional Climate Model (RCM) that drive a relatively simple, semi-distributed rainfall-runoff model (HBV-Light). Firstly, the GPP and observed rainfall were used to calibrate the model simulating streamflow dynamics. Secondly, drought detection and estimates of drought duration, intensity and severity were determined with a daily variable threshold approach. Thirdly, we developed future hydrological drought scenarios based on a RCM. Generally, the GPP CHIRPS (Climate Hazards Group InfraRed Precipitation with Station Data) resulted in the best streamflow simulations (KGE > 0.6) compared with the model driven by observed rainfall (KGE > 0.7). CHIRPS also correctly identified the observed streamflow drought periods of 1994, 1997-1998 and 2001-2002.Average observed streamflow drought severity was 27.9 mm compared to the CHIRPS-derived severity of 20.6 mm (error estimate of ±7.3 mm). The model in combination with global data can be successfully used to identify drought periods and their duration, but model uncertainty currently prevents from forecasting streamflow deficit with volume errors below 50%. The future hydrological drought scenario showed more severe drought periods between 2039-2041 and 2042-2043.This study responds to the need for drought assessments in the seasonally-dry tropics with scarce observations as a tool for adaptation to climate change and water resource management.
Background: Despite the key role topsoil plays in reclamation, there are situations where topsoil is in deficit or unavailable, especially at degraded and abandoned mine sites in Ghana. The sites pose serious ecological and safety risks, underscoring the urgent need to finding alternative substrate for restoration. This study investigated the feasibility of using amended-subsoil as topsoil substitute for reclamation. The hypothesis was that amendment of stockpiled-subsoil with poultry manure positively influences tree growth and ground vegetation cover (GVC), which promote better soil stabilization at degraded mine sites. A graded waste-rock dump was covered with a 70 cm layer of the stockpiled subsoil at Newmont Ghana Gold Limited. Two experimental plots (24 × 15 m) were established with the treatments poultry manure (PLM 23 t ha-1) and control (no PLM), followed by seeding of Cowpea (Vigna unguiculata) and planting of potted-seedlings of five forest tree species. The Laser-point-quadrat method was used to estimate GVC, whereas erosion was visually observed. Diameter and height data of planted trees and surviving numbers were collected.Results: There was significant increase in tree growth and in GVC for the poultry manure treatment compared to the control. The manure provided sufficient nitrogen to overcome nitrogen deficiency and facilitated quicker and stronger vegetation growth that yielded superior soil stabilization.Conclusions: The findings demonstrate the potential of manure application in promoting successful restoration of the many degraded and abandoned mine sites in Ghana to productive uses.
Photovoltaics (PV) are a rapidly growing technology as global energy sectors shift towards “greener” solutions. Despite the clean energy benefits of solar power, photovoltaic panels and their structural support systems (e.g., cement) often contain several potentially toxic elements used in their construction. Determining whether these elements have the potential to leach into surrounding environments should be a research priority, as panels are already being implemented on a large scale. In this study, we analyzed soil taken from beneath photovoltaic modules to determine if they are being enriched by metals (lead, cadmium, lithium, strontium, nickel, barium, zinc, and copper) and metalloids (selenium) present in panel systems. The soil samples were collected from directly beneath c-Si photovoltaic modules and adjacent fields. Samples were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES). Selenium, strontium, lithium, nickel, and barium levels measured in soil samples increased significantly in samples closer to PV systems. There were no significant differences in lead or cadmium levels near vs. far from the PV systems. Despite concentration differences for some elements near vs. far from the panel systems, no elements were, on average, present in concentrations that would pose a risk to nearby ecosystems. PV systems thus remain a cleaner alternative to traditional energy sources, such as coal, especially during the operation of these energy production systems.
Globally, clean cookstoves represent the best substitute for open fire biomass stoves in order to reduce greenhouse gas emissions from fuelwood. Prospects to transfer this technology to Botswana are being explored. Our research objectives were to transfer the clean Institutional Cookstove (IC) technology to Okavango Research Institute (ORI), quantify the amount of mopane (Colophospermum mopane) fuelwood it consumes in comparison to the traditional biomass energy system, and analyze its potential to be used as a substitute for the open fire cooking method. The clean IC technology transfer to ORI was successfully completed before testing its energy efficiency and financial viability. It consumed approximately two-thirds less fuelwood than the traditional three stone stove. This presents an opportunity for a reduction in greenhouse gas emissions from fuelwood consumption in Botswana. This is a critical consideration in an environment where there is limited readily available fuelwood. The use of clean cookstoves allows enhanced carbon sequestration by live mopane woodland resources. A financial viability analysis of implementing the clean IC in primary schools showed that it has the potential to save money spent on fuelwood. Our case study provides essential pertinent results on the energy efficiency of the developed prototype, which forms a basis for further research on the use of clean cookstoves for mitigating greenhouse gas emissions from fuelwood consumption in Botswana and the entire Cubango-Okavango River Basin. A comprehensive analysis of cultural barriers to adoption of the technology will be carried out through piloting the construction of the clean cookstove.
