Is there enough water? How bearish and bullish outlooks are linked to decision maker perspectives on environmental flows

Policy analysis for informing climate adaptation, environmental resilience, and irrigation demands in the Rio Grande Basin

Water policymakers internationally face the challenge of adapting to climate, supporting environmental resource needs, and meeting irrigation demands for food security in the world's arid and semi-arid regions. Much recent work has assessed the economic performance of environmental river flows to support endangered species habitat protection. However, little published work to date has systematically formulated and applied methods to identify the economic performance of various policy measures that adapt to climate, support endangered species, and meet irrigation demands for water. This work's original contribution with international relevance is to address those gaps by identifying the economic performance of various water shortage sharing methods for handling climate water stress while supporting protection of critical habitat to protect the endangered Southwestern willow flycatcher (Empidonax traillii extimus) along with Willow tree (Salix bonplandiana) habitat in the middle part of the Rio Grande Basin in North America, a region facing a number of conflicts between commercial uses of water and protection of key ecological assets. It develops a hydroeconomic optimization model containing information on crop water use and endangered species requirements in that region to identify the economic performance of three climate adaptation policy scenarios for handling water shortages while respecting endangered species habitat protection requirements. Results show how water shortages as well as policy responses for handing those shortages affect the economic value of water in agriculture for food security both with and without critical habitat to support the endangered flycatcher. This work's international relevance comes from its capacity to inform policy debates on the costs of protecting endangered species habitat under various climate scenarios and climate policy adaptation measures. Findings provide a general framework to address existing gaps in understanding and measuring the economic performance of measures to promote environmental resilience.

Beyond a 'just add water' perspective: environmental water management for vegetation outcomes

Practitioners of environmental water management (EWM) operate within complex social-ecological systems. We sought to better understand this complexity by investigating the management of environmental water for vegetation outcomes. We conducted an online survey to determine practitioners' perspectives on EWM for non-woody vegetation (NWV) in the Murray-Darling Basin, Australia with regards to: i) desirable outcomes and benefits; ii) influencing factors and risks; iii) challenges of monitoring and evaluation, and iv) improving outcomes. Survey participants indicated that EWM aims to achieve outcomes by improving or maintaining vegetation attributes and the functions and values these provide. Our study reveals that EWM practitioners perceive NWV management in a holistic and highly interconnected way. Numerous influencing factors as well as risks and challenges to achieving outcomes were identified by participants, including many unrelated to water. Survey responses highlighted six areas to improve EWM for NWV outcomes: (1) flow regimes, (2) vegetation attributes, (3) non-flow drivers, (4) management-governance considerations, (5) functions and values, and (6) monitoring, evaluation and research. These suggest a need for more than 'just water' when it comes to the restoration and management of NWV. Our findings indicate more integrated land-water governance and management is urgently required to address the impacts of non-flow drivers such as pest species, land-use change and climate change. The results also indicate that inherent complexity in EWM for ecological outcomes has been poorly addressed, with a need to tackle social-ecological constraints to improve EWM outcomes.

Protecting environmental flows to achieve long-term water security

In this work, we propose a new approach to diagnose if a water allocation scheme is compatible with long-term water security at the catchment scale, and suggest steps to achieve such compatibility. We argue that when the remaining flow of a river after upstream withdrawals is not sufficient to safeguarding ecological river functions, the basin is at extreme risk of water scarcity, which indicates that the water management is failing. To test this, we analysed the water scarcity risks and the safeguarded environmental flows (e-flows) in 277 basins across a wide range of hydro-climatic conditions in Chile (17-55°S). For each basin, water scarcity risks were assessed based on water stress indices (WSIs, computed as the ratio of withdrawals to water availability), considering two water-use scenarios: (i) WSI_max, where total withdrawals correspond to the maximum consumptive water allowed by the law, i.e., where only the e-flows protected by law remain in the river, and (ii) WSI_alloc, where total withdrawals correspond to the actual allocated consumptive water uses within the basins. Further, we evaluated the adequacy of the water management system to protect ecological river functions by contrasting the e-flows protected in Chile with those safeguarded in six other countries. The water allocation system in Chile incorporated the protection of minimum e-flows in 2005 and established that these do not exceed 20% of the mean annual streamflow, except in some exceptional cases. This upper limit is consistently lower than the e-flows safeguarded in other countries, where 20%-80% of the mean annual streamflow are protected. This turns out in WSI_max values between 80% and 100% in all basins, well above the threshold associated with over-committed basins under extreme risk of water scarcity (70% typically). When moving from the legally allowed to the actually allocated water use scenario, we found contrasting results: about 70% of the basins show low water scarcity risk (WSI_alloc <40%), while an 18% have WSI_alloc above 100%, indicating the allocation is going beyond current law limits and even beyond physical limits. Our results reveal that the link between e-flows, water allocation and water security has not been adequately incorporated in the current law. E-flows stipulated by law are insufficient to fulfil environmental requirements, while placing the basins under extreme risk of water scarcity if the total allowed withdrawals were exerted. To move towards a system that can effectively achieve long-term water security, we recommend: (i) To define tolerable water scarcity risks for basins, considering environmental requirements. (ii) To translate those risks into measurable basin indices to measure water security, such as the WSI. (iii) To set maximum water use limits (or minimum e-flows) within the basins that are compatible to the water security goals. If, under current and projected water availability conditions, the existing withdrawals exceed these limits, water managers should be able to adapt total consumption to the required limits.

Habitat alteration assessment for the management of environmental flows in regulated basins

The management of environmental flows is of paramount importance in regulated water resources systems to preserve river ecosystems. This work proposes a methodology to assess habitat alteration in river basins altered by management activities. The methodology is based on the joint application of a basin management model (SIMGES, AQUATOOL) and a model to estimate habitat time series (CAUDECO). CAUDECO is based on the weighted useable areas of the species in their different vital stages that, in turn, depend on the flows in each river stretch and the biological periods of the species. The final output is an indicator of habitat alteration, which is defined ad hoc for this work to relate the habitat suitability under regulated and natural regimes. The methodology was applied to a case study in north-western Spain: the Órbigo River basin. The results in the current management scenario highlight that the ecological flows improve the habitat suitability of several species with respect to natural regime conditions. For instance, the mean values of the habitat time series in the Órbigo River for the brown trout and bermejuela under regulated conditions are 69.6% and 88%; whereas in natural regime they are equal to 55.1% and 72.9%, respectively. Based on these results, eight additional scenarios of ecological flows were tested and their effects on both habitat alteration and water demand reliability were quantified and discussed. It was found that increases in the ecological flows up to 30% do not affect the reliability of water demands and reduce habitat alteration (i.e., lead to values of the habitat alteration indicator closer to 1) for all species present in the river basin. These results highlight that the methodology and indicator of habitat alteration proposed in this paper are useful to support the management of regulated river basins, since they allow assessing the implications of ecological flows on both habitat suitability and reliability of water demands.

Automated environmental compliance monitoring of rivers with IoT and open government data

Environmental monitoring of rivers is a cornerstone of the European Union's Water Framework Directive. It requires the estimation and reporting of environmental flows in rivers whose characteristics vary widely across the EU member states. This variability has resulted in a fragmentation of estimation and reporting methods for environmental flows and is exhibited by the myriad of regulatory guidelines and estimation procedures. To standardise and systematically evaluate environmental flows at the pan-European scale, we propose to formalise the estimation procedures through automation by reusing existing river monitoring resources. In this work, we explore how sensor-generated hydrological open government data can be repurposed to automate the estimation and monitoring of river environmental flows. In contrast to existing environmental flows estimation methods, we propose a scalable IoT-based architecture and implement its cloud-layer web service. The major contribution of this work is the demonstration of an automated environmental flows system based on open river monitoring data routinely collected by national authorities. Moreover, the proposed system adds value to existing environmental monitoring data, reduces development and operational costs, facilitates streamlining of environmental compliance and allows for any authority with similar data to reuse or scale it with new data and methods. We critically discuss the opportunities and challenges associated with open government data, including its quality. Finally, we demonstrate the proposed system using the Estonian national river monitoring network and define further research directions.