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A novel strategy for estimating groundwater recharge in arid mountain regions and its application to parts of the Jebel Akhdar Mountains (Sultanate of Oman)

Alexander Gerner1
1 Dr. Dittrich & Partner Hydro-Consult GmbH

O 10.7 in Hydrogeologie arider Gebiete

30.05.2014, 19:20-19:40, H17, NW II

In arid regions, mountain catchments are the major contributor to the total natural water yield. Due to generally low groundwater tables, subsurface underflow is important in distinction to the surface runoff at the mountain front. The extent of the groundwater basin is hereby often vague. Approaches to assess the subsurface fluxes are mostly based on groundwater data and integrate over time and space. This, however, cannot provide prognostic and time-dependent estimates of subsurface inflow to the adjacent alluvial basin aquifer. Consequently, the proposed strategy builds on rainfall based approaches. Temporal and spatial resolution is in this case mostly limited by data scarcity regarding hydrological characteristics of the catchment area and high-resolution rainfall data.

The proposed novel strategy combines three approaches to tackle these challenges. A newly developed conceptual hydrologic model provides time-dependent estimates based on fully distributed monthly rainfall. For distinct response units and seasons, non-linear relationships between rainfall and recharge describe the hydrogeologic response. The derivation of the response functions is based on a mass balance and considers the principal recharge mechanisms. Parameterisation makes use of available expert knowledge on geomorphology and seasonal rainfall characteristics. As an efficient tool to assess uncertainties, fuzzy arithmetic is used for complementary long-term average water balance estimates. This technique allows considering fuzziness in rainfall input, crop water use in mountain oases, and best available assumptions on recharge as portion of rainfall. Uncertainty regarding the potential, albeit unknown extent of groundwater basins is portrayed based on fuzzy regions, i.e. continuous surfaces which represent geographic entities. Distinct subsets of these fuzzy regions represent potential groundwater basins for water balance assessment.

The proposed strategy has been applied on the large scale in an arid karst mountain range in northern Oman. The two complementary assessment approaches result in similar ranges of values. They are in good agreement with inversely computed inflow to a steady state groundwater model for the adjacent basin aquifer. The results of the conceptual hydrologic model are confirmed by the plausibility of average recharge rates for distinct response units and seasons.

 



GERNER, A., N. SCHÜTZE, and G. H. SCHMITZ (2012): Portrayal of fuzzy recharge areas for water balance modelling – a case study in northern Oman, Adv. Geosci., 31, 1-7, doi:10.5194/adgeo-31-1-2012.

GERNER, A. (2014): A novel strategy for estimating groundwater recharge in arid mountain regions and its application to parts of the Jebel Akhdar Mountains (Sultanate of Oman). Dresdner Schriften zur Hydrologie, Band 11. TU Dresden, Dresden. 128 pp. nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-137045 (March 10, 2014).



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Letzte Änderung 14.05.2014