GroMoPo Metadata for Regueb basin model

Climate and anthropogenic changes are expected to reduce renewable groundwater resources and to increase the risks of water scarcity, particularly in arid regions. Understanding current and future risks of water scarcity is vital to make the right water management decision at the right time. This study aims to analyze the impact of both human and climate pressures on groundwater availability in an arid environment: the Regueb basin in Central Tunisia. An integrated approach was used and applied at a monthly time step over a reference period (1976-2005) and a future period (2036-2065). Groundwater resources were assessed using hydrogeological modeling. Irrigation water withdrawals were evaluated based on remote sensing and the CropWat model. Urban water use was estimated from population growth and specific monthly water consumption data. The resulting values were used to compute two indicators (water stress index, groundwater balance) to evaluate water scarcity risks at the 2050 horizon. To assess current and future climate forcing on water resources, three climate scenarios were generated based on simulations from Coupled Model Intercomparison Project Phase 5 (CMIP5) data. A business-as-usual and an adaptation scenario (optimal cropping scenario) were performed by varying the surface areas and the crops grown in the irrigated area. Results show that the average annual water use will increase by 3.8 to 16.4% under climate change only, whereas it will increase by 100% under the business-as-usual scenario. Under the optimal cropping scenario, total water demand will increase by 50%. Water stress index indicates that under the climate change only scenario, water demand should be satisfied by the 2050 horizon, while under the other two scenarios, severe water stress will occur by 2050. The developed framework in this paper aims to fit in arid and semiarid regions in order to evaluate groundwater stress and to assess the efficiency of adaptation strategies. It results in two major recommendations regarding changes in land use and the improvement of groundwater monitoring.

气候变化与人类活动变化预计将减少可再生地下水资源，并加剧水资源短缺风险，在干旱地区尤为显著。明晰当前与未来的水资源短缺风险，对于适时制定合理的水资源管理决策至关重要。本研究旨在剖析干旱环境下（突尼斯中部雷格布盆地）人类活动与气候压力对地下水可获得性的影响。研究采用集成化研究方法，以月为时间步长，在基准时段（1976-2005年）与未来时段（2036-2065年）开展应用分析。通过水文地质建模对地下水资源进行评估；基于遥感技术与CropWat模型，对灌溉取水量进行核算；结合人口增长数据与特定月均用水量数据，估算城市用水量。将上述核算所得数值用于计算两项指标——水资源压力指数（water stress index）与地下水均衡（groundwater balance），以评估2050年水平下的水资源短缺风险。为评估当前及未来气候驱动对水资源的影响，本研究基于耦合模式比较计划第五阶段（CMIP5）的模拟数据，生成了三种气候情景。通过改变灌溉区的种植面积与作物类型，分别设置了常规发展情景与适应型情景（最优种植情景）。研究结果显示：仅考虑气候变化情景下，年均用水量将增长3.8%至16.4%；而在常规发展情景下，年均用水量将增幅达100%。在最优种植情景下，总需水量将增长50%。水资源压力指数结果表明：仅考虑气候变化情景下，至2050年水资源需求可得到满足；而在其余两种情景下，至2050年将出现严重水资源短缺问题。本文构建的研究框架适用于干旱与半干旱地区，可用于评估地下水压力及适应策略的实施成效。研究最终提出两项核心建议，分别涉及土地利用调整与地下水监测体系优化。