Water-scarcity patterns : spatiotemporal interdependencies between water use and water availability in a semi-arid river basin

This thesis addresses the interdependencies between water use and water availability and describes a model that has been developed to improve understanding of the processes that drive changes and variations in the spatial and temporal distribution of water resources in a semi-arid river basin. These processes include hydrological processes and water user responses to variations and changes in water availability. The results are relevant for climate change impact assessments and river basin management, in particular for water allocation in semi-arid environments.\ud The Jaguaribe basin in the northeast of Brazil was used as a case study. Concepts from the literature on common-pool resources were applied to analyse the extent to which the physical characteristics of a river basin facilitate or impede sustainable management of water resources in different parts of the Jaguaribe basin. The relationship between water use and water availability in a sub-basin of the Jaguaribe basin was explored. The obtained knowledge was used to design and test a multi-agent simulation approach implemented by using remotely-sensed land use data and survey data on water user decision making.\ud It was found that for the Jaguaribe basin a decrease in rainfall and runoff typically leads to a transition of irrigation water use not only from water-scarce periods to less water-scarce periods, but also from downstream areas to upstream areas. Strategic reservoir operation enables local water managers to offset the effect of decreasing rainfall and runoff with respect to irrigation water use at the sub-basin level, at the cost of further decreasing water availability at the basin level.\ud It is concluded that the theory of common-pool resources and that the concept of downstreamness, introduced and quantitatively defined in this thesis, are helpful in assessing the manageability of water resources in a river basin. Further, a multi-agent simulation approach has proven instrumental in studying interactions between water users and water resources

Sustainability of small reservoirs and large scale water availability under current conditions and climate change

Semi-arid river basins often rely on reservoirs for water supply. Small reservoirs may impact on large-scale water availability both by enhancing availability in a distributed sense and by subtracting water for large downstream user communities, e.g. served by large reservoirs. Both of these impacts of small reservoirs are subject to climate change. Using a case-study on North-East Brazil, this paper shows that climate change impacts on water availability may be severe, and impacts on distributed water availability from small reservoirs may exceed impacts on centralised water availability from large reservoirs. Next, the paper shows that the effect of small reservoirs on water availability from large reservoirs may be significant, and increase both in relative and absolute sense under unfavourable climate change

Drivers of groundwater utilization in water-limited rice production systems in Nepal

Most rice farmers in Nepal’s Terai region do not fully utilize irrigation during breaks in monsoon rainfall. This leads to yield losses despite abundant groundwater resources and ongoing expansion of diesel pumps and tubewell infrastructure. We investigate this puzzle by characterizing delay factors governing tubewell irrigation across wealth and precipitation gradients. After the decision to irrigate, different factors delay irrigation by roughly one week. While more sustainable and inexpensive energy for pumping may eventually catalyze transformative change, we identify near-term interventions that may increase rice farmers’ resilience to water stress in smallholder-dominated farming communities based on prevailing types of irrigation infrastructure.</p

Twenty-three unsolved problems in hydrology (UPH) – a community perspective

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through on-line media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focussed on process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come

Data underlying the publication : "A review of drought indices: predominance of drivers over impacts and the importance of local context"

This dataset has been used to determine the country of application of different drought related studies, focusing on both categories of drought indicators and drought impacts

Water-related limits to growth for agriculture in Iran

Globally, agriculture is the primary water consumption sector. This study used water footprint (WF) as a bottom-up tool and satellite imagery as a top-down tool to estimate the internal water use (WU) in the agricultural sector in an innovative way to show the effects of water-intensive use in agriculture in an arid country. The WF of Iran has been quantified for 19 main crops and for related agricultural products exported from Iran to partner countries. Using a bottom-up approach, Iran's total yearly agriculture net water consumption is estimated to be 42.43 billion cubic meters (BCM) per year. Out of 42.43 BCM total net internal water use, only 1.61 BCM is virtual-water export related to these 19 products, and the remaining 40.82 BCM is for internal use. Our results using satellite imagery show that in case of using all possible lands for agriculture, it would require 77.4 BCM. However, not all these lands are within human reach, and the maximum available water is way lower than this amount. Using satellite imagery, the total evaporation from agricultural lands shows 55.27 BCM for 2020, which agrees with national reports during 2005–2014. This study shows that agricultural water consumption tends to use internal water resources at a maximum level for export and national use, significantly impacting renewable and non-renewable water resource availability, especially in groundwater