Endorheic basins around the world are suffering from water and ecosystem crisis. To pursue sustainable development, quantifying the hydrological cycle is fundamentally important. However, knowledge gaps exist in how climate change and human activities influence the hydrological cycle in endorheic basins. We used an integrated ecohydrological model, in combination with systematic observations, to analyze the hydrological cycle in the Heihe River Basin, a typical endorheic basin in arid region of China. The water budget was closed for different landscapes, river channel sections, and irrigation districts of the basin from 2001 to 2012. The results showed that climate warming, which has led to greater precipitation, snowmelt, glacier melt, and runoff, is a favorable factor in alleviating water scarcity. Human activities, including ecological water diversion, cropland expansion, and groundwater overexploitation, have both positive and negative effects. The natural oasis ecosystem has been restored considerably, but the overuse of water in midstream and the use of environmental flow for agriculture in downstream have exacerbated the water stress, resulting in unfavorable changes in surface‐ground water interactions and raising concerns regarding how to fairly allocate water resources. Our results suggest that the water resource management in the region should be adjusted to adapt to a changing hydrological cycle, cropland area must be reduced, and the abstraction of groundwater must be controlled. To foster long‐term benefits, water conflicts should be handled from a broad socioeconomic perspective. The findings can provide useful information on endorheic basins to policy makers and stakeholders around the world.

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This research aims to determine the impacts caused by the endogenous change factor of land use and different policies related to water resource management in a hydrographic watershed over the socio-ecological system associated with it. This research focuses on the Santa Elena township (Medellín, Colombia) districts El Llano, El Plan, Santa Elena Central, and Perico.where the San Pedro micro-watershed is located.San Pedro micro-watershed supplies water to 1034 users and ecological reforestation was carried out there by the Municipality of Medellín. Based on this information collected in the field and complemented documentation review, the interactions and strength of social and ecological networks are analyzed to identify the structure and behavior of the socio-ecological system of the present study. This research shows the development of the socio-ecological system in a simulation model representing the system dynamics which aims to identify the impacts caused by water resource management policies and the influence of endogenous population growth. The results demonstrate that the most important impact generated by the endogenous influence and the execution of water resource management policies within the socio-ecological system of the San Pedro micro-watershed is the reduction of the land designated to agriculture, thus generating changes in the traditional economic activities of the territory of study. Likewise, the effects generated by the application of the policy of water resource management are efficient, and that guarantees the water supply in the San Pedro stream, despite the demand increasing of domestic water.

This study quantified the hydrological responses to land-use change scenarios in the upper and middle Heihe River basin (HRB), northwest China, under constant and changed climatic conditions by combining a land-use/cover change model (dynamic conversion of land use and its effects, Dyna-CLUE) and a hydrological model (soil and water assessment tool, SWAT). Five land-use change scenarios, i.e., historical trend (HT), ecological protection (EP), strict ecological protection (SEP), economic development (ED), and rapid economic development (RED) scenarios, were established. Under constant climatic condition, hydrological variations are only induced by land-use changes in different scenarios. The changes in mean streamflow at the outlets of the upper and the middle HRB are not pronounced, although the different scenarios produce different outcomes. However, more pronounced changes are observed on a subbasin level. The frequency of extreme flood is projected to decrease under the SEP scenario, while under the other scenarios, no changes can be found. Two emission scenarios (A1B and B1) of three general circulation models (HadCM3, CGCM3, and CCSM3) were employed to generate future possible climatic conditions. Under changed climatic condition, hydrological variations are induced by the combination of land-use and climatic changes. The results indicate that the impacts of land-use changes become secondary when the changed climatic conditions have been considered. The frequencies of extreme flood and drought are projected to decrease and increase, respectively, under all climate scenarios. Although some agreements can be reached, pronounced difference of hydrological responses can be observed for different climate scenarios of different GCMs.

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Watershed system models are urgently needed to understand complex watershed systems and to support integrated river basin management. Early watershed modeling efforts focused on the representation of hydrologic processes, while the next‐generation watershed models should represent the coevolution of the water‐land‐air‐plant‐human nexus in a watershed and provide capability of decision‐making support. We propose a new modeling framework and discuss the know‐how approach to incorporate emerging knowledge into integrated models through data exchange interfaces. We argue that the modeling environment is a useful tool to enable effective model integration, as well as create domain‐specific models of river basin systems. The grand challenges in developing next‐generation watershed system models include but are not limited to providing an overarching framework for linking natural and social sciences, building a scientifically based decision support system, quantifying and controlling uncertainties, and taking advantage of new technologies and new findings in the various disciplines of watershed science. The eventual goal is to build transdisciplinary, scientifically sound, and scale‐explicit watershed system models that are to be codesigned by multidisciplinary communities.