IAHS-AISH publication 

About: IAHS-AISH publication is an academic journal. The journal publishes majorly in the area(s): Groundwater & Surface runoff. It has an ISSN identifier of 0144-7815. Over the lifetime, 4560 publications have been published receiving 30863 citations.

Climate change and water resources

Abstract: The consideration of the impact of climate on water resources is placed in a wider context: the chain reaction associated with such an impact crosses the interfaces between climate, hydrology, water-resource systems and society. Each interface demands collaboration and exchange of information between specialists and assurance that current tools and approaches are appropriate for the new environment that may evolve. The chain reaction must be studied from start to finish if the final impact on water resources is to be assessed. Various points are presented for consideration at each stage. Impact du climat sur les ressources en eau RESUME La consideration de l'impact du climat sur les ressources en eau est placee dans un contexte plus large: la reaction en chaine associee a un tel impact comprend les domaines communs au climat, a l'hydrologie, aux systemes de ressources en eau et a la societe. Chaque domaine commun necessite la collaboration et l'echange d'informations entre les specialistes et l'assurance que les outils et approches actuels soient appropries au nouvel environnement susceptible d'evoluer. La reaction en chaine doit etre etudiee du de'but a la fin si l'impact final sur les ressources en eau doit etre evalue. Differents points sont presentes pour etre consideres a chaque stade.

Role of supraglacial ponds in the ablation process of a debris-covered glacier in the Nepal Himalayas

Abstract: There are many supraglacial ponds on debris-covered glaciers in the Nepal Himalayas. The heat absorbed at the surface of a pond was estimated from heat budget observations on the Lirung Glacier in Langtang Valley, Nepal. The results indicated an average heat absorption of 170 W m -2 during the summer monsoon season. This rate is about 7 times the average for the whole debris-covered zone. Analysis of the heat budget for a pond suggests that at least half of the heat absorbed at a pond surface is released with the water outflow from the pond, indicating that the water warmed in the pond enlarges the englacial conduit that drains water from the pond and produces internal ablation. Furthermore, the roof of the conduit could collapse, leading to the formation of ice cliffs and new ponds, which would accelerate the ablation of the debris-covered glacier.

A Spatially Distributed Energy Balance Snowmelt Model

Abstract: This paper describes an energy balance snowmelt model developed for the prediction of rapid snowmelt rates responsible for soil erosion and water input to a distributed water balance model. The model uses a lumped representation of the snowpack with two primary state variables, namely, water equivalence and energy content relative to a reference state of water in the ice phase at 0oC. This energy content is used to determine snowpack average temperature or liquid fraction. This representation of the snowpack is used in a distributed version of the model with each of these state variables modeled at each point on a rectangular grid corresponding to a digital elevation model. Inputs are air temperature, precipitation, wind speed, humidity and radiation at hourly time steps. The model uses physically-based calculations of radiative, sensible, latent and advective heat exchanges. An equilibrium parameterization of snow surface temperature accounts for differences between snow surface temperature and average snowpack temperature without having to introduce additional state variables. Melt outflow is a function of the liquid fraction, using Darcy's law. This allows the model to account for continued outflow even when the energy balance is negative. A detailed description of the model is given together with results of tests against data collected at the Central Sierra Snow Laboratory, California; Reynolds Creek Experimental Watershed, Boise Idaho; and at the Utah State University drainage and evapotranspiration research farm, Logan Utah. The testing includes comparisons against melt outflow collected in melt lysimeters, surface snow temperatures collected using infrared temperature sensors and depth and water equivalence measured using snow core samplers.

Practical prediction of ice melting beneath various thickness of debris cover on Khumbu Glacier, Nepal, using a positive degree-day factor

Abstract: Ice ablation on bare ice and under various thickness of debris was measured on Khumbu Glacier from 21 May to 1 June 1999 in order to study how debris affects the relationship between positive degree-day factor and ablation rate. Results for a debris cover ranging in thickness from 0 to 5 cm show that ice ablation is enhanced by a maximum at 0.3 cm. Debris thicker than 5 cm retards ablation. Although meteorological measurements show that the main energy source for ablation is net radiation (about 96% of total energy available for ablation on bare ice) the positive degree-day factor is nevertheless a successful predictor. For ice ablation on bare ice it is 16.9 mm day -1 °C -1 . Under 10- and 40-cm-thick debris layers, the factors are 11.1 and 5.3 mm day -1 °C -1 , respectively. The data required to predict ice ablation under a debris layer are ablation rate on bare ice, ratio of degree-day factor for debris cover to bare ice based on thermal resistance for the critical debris thickness and effective thermal resistance of the debris cover.