Optimization of Groundwater Exploitation in an Irrigation Area in the Arid Upper Peacock River, NW China: Implications for Sustainable Agriculture and Ecology

Groundwater is the main irrigation water source in the Upper Peacock River. As fast enlargement of irrigation areas continues in recent years, the groundwater level declines continuously and has posed a threat to the sustainability of local agriculture and ecology. A numerical model was established with the code MODFLOW–2000 in order to predict the declining trend of groundwater level and formulate measures to counter the overexploitation, in which the river–aquifer interaction was elaborated and characterized by field survey. The results show that under current intensity of groundwater withdrawal, the levels of both unconfined and confined waters would decline continuously in 7 years from 2015. To stop the groundwater level from declining on the regional scale, the withdrawal rate should be compressed by 45% with respect to that in 2015. Moreover, taking consideration of the constraint of maintaining the ecological water level in the vicinity of the Euphrates Poplar forest in the study area, the withdrawal rate should be compressed 70% for seven towns around the forest.

Unraveling the Water-Energy-Food-Environment Nexus for Climate Change Adaptation in Iran: Urmia Lake Basin Case-Study

A holistic approach to the management of water, energy, food, and the environment is required to both meet the socioeconomic demands of the future as well as sustainable development of these limited resources. The Urmia Lake Basin has faced environmental, social, and economic challenges in recent years, and this situation is likely to worsen under the impacts of climate change. For this study, an adaptability analysis of this region is proposed for the 2040 horizon year. Two models, the water evaluation and planning (WEAP (Stockholm Environmental Institute, Stockholm, Sweden)) and the low emissions analysis platform (LEAP (Stockholm Environmental Institute, Boston, MA, USA)), are integrated to simulate changes in water, energy, food, and the environment over these 20 years. Two climate scenarios and nine policy scenarios are combined to assess sustainable development using a multi-criteria decision analysis (MCDA) approach. Results show that, through pursuing challenging goals in agricultural, potable water, energy, and industrial sectors, sustainable development will be achieved. In this scenario, the Lake Urmia water level will reach its ecological water level in 2040. However, social, technical, and political challenges are considered obstacles to implementing the goals of this scenario. In addition, industry growth and industry structure adjustment have the most impact on sustainable development achievement.

Assessing the Ecological Water Level: The Case of Four Mediterranean Lakes

The ecological water regime in lake water bodies refers to the water levels that enable the fulfillment of the ecosystem’s multiple functions. Therefore, assessing the ecological water regime necessitates the consideration of hydrological, economic, social, and ecological factors. The present research is focused on the assessment of the ecological water level of four Mediterranean natural lake ecosystems, considering their morphological and biological features. Initially, suggestions on the ecological water regime of the studied lakes were made based on an analysis of the lakes’ morphometry. Further, the ecological and biological requirements of the present fish fauna and aquatic macrophytic vegetation were considered. For the latter, mapping was conducted by extensive sampling according to international standards, in order to assess macrophyte composition, abundance, and chorology, as well as species sensitivity to water level fluctuations. The above guided the proposals on the optimal water level regime that should be met by each lake regarding the macrophytic and fish communities’ sustainability, also taking into account the unique hydromorphological features of each lake. The differences in the outcoming results revealed that hydromorphological and biological approaches should be combined for assessing lakes’ ecological water regimes.

Simplified Lake Surface Area Method for the Minimum Ecological Water Level of Lakes and Wetlands

The determination of the rational minimum ecological water level is the base for the protection of ecosystems in shrinking lakes and wetlands. Based on the lake surface area method, a simplified lake surface area method was proposed to define the minimum ecological lake level from the lake level-logarithm of the surface area curve. The curve slope at the minimum ecological lake level is the ratio of the maximum lake storage to the maximum surface area. For most practical cases when the curve cannot be expressed as a simple analytical function, the minimum ecological lake level can be determined numerically using the weighted sum method for an equivalent multi-objective optimization model that balances ecosystem protection and water use. This method requires fewer data of lake morphology and is simple to compute. Therefore, it is more convenient to use this method in the assessment of the ecological lake level. The proposed method was used to determine the minimum ecological water level for one freshwater lake, one saltwater lake, and one wetland in China. The results can be used in the lake ecosystem protection planning and the rational use of water resources in the lake or wetland basins.

Simulation of multiple water source ecological replenishment for Chagan Lake based on coupled hydrodynamic and water quality models

Chagan Lake serves as an irrigation storage reservoir for the Qianguo Irrigation Area and an important ecological barrier in western Jilin. The coupled TUFLOW-FV and Aquatic Ecodynamic (AED2) models were used to simulate the hydrodynamic and water quality of Chagan Lake, and propose the water diversion scheme that could improve the water quality to reach Grade III and maintain the ecological water level. The simulation results showed a satisfactory agreement with observations. The total carrying loads of NH3-N, total nitrogen (TN) and total phosphorus (TP) for Chagan Lake were 1,147.6, 3,686.2 and 100.8 t from May to October. The range of the minimum amounts of water diversion to keep the water quality as Grade III and maintain the maximum ecological water level of 131.5 m for TN, TP were separately [32.60, 49.84, 57.19, 63.70, 70.91], [117.25, 135.26, 168.17, 190.65, 218.32] million m3 and the corresponding reduction amounts of farmland drainage for TN, TP were separately [4.03, 0, 0, 0, 0], [73.08, 61.88, 50.23, 40.94, 31.98] million m3 under the rainfall guarantee rates of 10%, 20%, 50%, 75%, 90%, respectively. The simulation results provide a scientific basis for the water quality improvement and ecological water supplement required for the interconnected river–lake system network (IRLSN) in Western Jilin Province.