This paper presents a water resources sustainability index that makes it possible to evaluate and compare different water management policies with respect to their sustainability. The sustainability index identifies policies that preserve or improve the desired water management characteristics of the basin in the future. This index is based on a previous sustainability index with improvements in its structure, scale, and content to make it more flexible and adjustable to the requirements of each water user, type of use, and basin. The Rio Grande transboundary basin is used as a case study demonstrating the use of the index. Tailor-made sustainability indexes are defined for water users in Mexico, the United States, the environment, and for meeting system requirements (international treaty obligations). Group sustainability indexes are calculated to summarize the results for groups of water users of each country, the environment, and the basin as a whole. Sustainability indexes by subbasins are calculated ...

Glacial lakes in the Nepal Himalaya can threaten downstream communities and have large socio-economic consequences if an outburst flood occurs. This study identified 131 glacial lakes in Nepal in 2015 that are greater than 0.1 km² and performed a first-pass hazard and risk assessment for each lake. The hazard assessment included mass entering the lake, the moraine stability, and how lake expansion will alter the lake’s hazard in the next 15–30 years. A geometric flood model was used to quantify potential hydropower systems, buildings, agricultural land, and bridges that could be affected by a glacial lake outburst flood. The hazard and downstream impacts were combined to classify the risk associated with each lake. 11 lakes were classified as very high risk and 31 as high risk. The potential flood volume was also estimated and used to prioritize the glacial lakes that are the highest risk, which included Phoksundo Tal, Tsho Rolpa, Chamlang North Tsho, Chamlang South Tsho, and Lumding Tsho. These results are intended to assist stakeholders and decision makers in making well-informed decisions with respect to the glacial lakes that should be the focus of future field studies, modeling efforts, and risk-mitigation actions.

One of the consequences of recent glacier recession in the Cordillera Blanca, Peru, is the risk of glacial lake outburst floods (GLOFs) from lakes that have formed at the base of retreating glaciers. GLOFs are often triggered by avalanches falling into glacial lakes, initiating a chain of processes that may culminate in significant inundation and destruction downstream. This paper presents simulations of all of the processes involved in a potential GLOF originating from Lake Palcacocha, the source of a previously catastrophic GLOF on 13 December 1941, killing about 1800 people in the city of Huaraz, Peru. The chain of processes simulated here includes (1) avalanches above the lake; (2) lake dynamics resulting from the avalanche impact, including wave generation, propagation, and run-up across lakes; (3) terminal moraine overtopping and dynamic moraine erosion simulations to determine the possibility of breaching; (4) flood propagation along downstream valleys; and (5) inundation of populated areas. The results of each process feed into simulations of subsequent processes in the chain, finally resulting in estimates of inundation in the city of Huaraz. The results of the inundation simulations were converted into flood intensity and preliminary hazard maps (based on an intensity-likelihood matrix) that may be useful for city planning and regulation. Three avalanche events with volumes ranging from 0.5 to 3 × 10⁶ m³ were simulated, and two scenarios of 15 and 30 m lake lowering were simulated to assess the potential of mitigating the hazard level in Huaraz. For all three avalanche events, three-dimensional hydrodynamic models show large waves generated in the lake from the impact resulting in overtopping of the damming moraine. Despite very high discharge rates (up to 63.4 × 10³ m³ s⁻¹), the erosion from the overtopping wave did not result in failure of the damming moraine when simulated with a hydro-morphodynamic model using excessively conservative soil characteristics that provide very little erosion resistance. With the current lake level, all three avalanche events result in inundation in Huaraz due to wave overtopping, and the resulting preliminary hazard map shows a total affected area of 2.01 km², most of which is in the high hazard category. Lowering the lake has the potential to reduce the affected area by up to 35 %, resulting in a smaller portion of the inundated area in the high hazard category.

This paper presents an analysis of a newly developed draft agreement on the allocation of water and energy resources of the Syr Darya basin considering transboundary cooperation and benefits sharing. The method uses a river basin model and game theoretic concepts to assess the potential benefits to the four riparian countries, under various arrangements of cooperation, ranging from independent action to full cooperation as envisioned in the draft agreement. The analysis shows increased benefits to all countries in the basin if they follow the four-country cooperative arrangements outlined in the draft agreement. Different methods for allocating the benefits of cooperation are considered. The Shapely allocation provides each country with increased economic benefits and is stable in relation to each country’s likelihood of treaty compliance. Other methods to allocate of the gains are considered, such as proportional shares, equal shares, the Nucleolus, and Nash-Harsayni, which all result in allocations that...