| Title | Modeling Climate Change Impact on the Water Balance of a Coastal Watershed in Lebanon |
| Abstract | Water, a precious and valuable natural resource in the Middle East, is a limiting factor for its development. The possible climate alterations likely to impact the Region with increasing global air temperatures and changing in precipitation patterns would lead to a sensible modification of hydrological processes at regional and local scales. Analyzing the potential impacts of climatic changes is an important step toward adaptation and mitigation especially for countries with vulnerable water resources. The objective of this study is to develop basin scale climate change scenarios (CCS) for a coastal watershed in Lebanon, Nahr Ibrahim watershed (NIW), which is representative of the snow-melt dominated watersheds located in Mount Lebanon (the so called water tower of the Middle East). This is the main objective of the biennial research programme 2012-2013 for "Modelling Water Balance Using Remotely Sensed Data" funded under the Scientific Cooperation between the National Research Council of Italy (CNR) and the National Council for Scientific Research of Lebanon (CNRS-L). To this end the regional climate model PRECIS (Providing Regional Climates for Impact Studies) developed by Hadley Centre of U.K. was adopted as a dynamic downscaling of a global climate model (GCM) thus providing spatially detailed projections and scenarios of future climate over the area of interest at a resolution of about 25x25 km. Daily simulations for precipitation (P), maximum and minimum temperature (Tmax, Tmin) from PRECIS were adopted to evaluate the impact of climate change on the water balance of the NIW by taking into account the time series for the recent past (1980-2000), the present (2001-2011), the near future (2012-2032) and the distant future (2080-2098) and comparing them with the available climate observations in order to assess the possible future variation in precipitation and temperature. The available stations' observations were also used to derive monthly regressions between climate and topographic elevations to be adopted as a simple interpolation tool to estimate the spatial distribution of T and P in NIW. Changes in climate variables resulted significant for the near future only for T while in the distant future, both P and T showed respectively remarkable decrease and increase. These alterations will correspond to a decrease in snow-covered area and anticipated snow-melt thus altering the water balance of NIW both in terms of mean values and variability. To simulate the impacts on stream flow regimes, basin scale CCS were coupled with a conceptual water balance model named NIWaB that was previously developed and calibrated. A consistent module of the model was developed to capture the space-time dynamics of the snow cover and snowmelt contribution. Such computations allowed to assess the possible climate change impacts on the hydrological signature of NIW which resulted strongly influenced by a shorter snowy period and a consequent enhanced seasonality of the river flows. The results may be helpful in assessing the opportunity of a new artificial reservoir as a strategy for climate change adaptation by enabling the storage of winter and spring flows as well as the regulation of flood peaks. |
| Source | 1st CIGR Inter-Regional Conference on Land and Water Challenges, 10/09/2013-14/09/2013 |
| Keywords | climate change impactswater balance modellingMediterranean water resources |
| Year | 2013 |
| Type | Contributo in atti di convegno |
| Authors | Portoghese I., Saqallah S., Vurro M., Darwish T., Shaban A., Khadra R. |
| Text | 343742 2013 climate change impacts water balance modelling Mediterranean water resources Modeling Climate Change Impact on the Water Balance of a Coastal Watershed in Lebanon Portoghese I., Saqallah S., Vurro M., Darwish T., Shaban A., Khadra R. Istituto di Ricerca sulle Acque del Consiglio Nazionale delle Ricerche, IRSA CNR, viale F. De Blasio 5, 70132 Bari, Italy; CIHEAM, IAM Bari, via Ceglie 9, 70010 Valenzano BA , Italy; National Council for Scientific Research, Remote Sensing Center, P.O.Box 11 8281, Beirut, Lebanon; Water, a precious and valuable natural resource in the Middle East, is a limiting factor for its development. The possible climate alterations likely to impact the Region with increasing global air temperatures and changing in precipitation patterns would lead to a sensible modification of hydrological processes at regional and local scales. Analyzing the potential impacts of climatic changes is an important step toward adaptation and mitigation especially for countries with vulnerable water resources. The objective of this study is to develop basin scale climate change scenarios CCS for a coastal watershed in Lebanon, Nahr Ibrahim watershed NIW , which is representative of the snow melt dominated watersheds located in Mount Lebanon the so called water tower of the Middle East . This is the main objective of the biennial research programme 2012 2013 for Modelling Water Balance Using Remotely Sensed Data funded under the Scientific Cooperation between the National Research Council of Italy CNR and the National Council for Scientific Research of Lebanon CNRS L . To this end the regional climate model PRECIS Providing Regional Climates for Impact Studies developed by Hadley Centre of U.K. was adopted as a dynamic downscaling of a global climate model GCM thus providing spatially detailed projections and scenarios of future climate over the area of interest at a resolution of about 25x25 km. Daily simulations for precipitation P , maximum and minimum temperature Tmax, Tmin from PRECIS were adopted to evaluate the impact of climate change on the water balance of the NIW by taking into account the time series for the recent past 1980 2000 , the present 2001 2011 , the near future 2012 2032 and the distant future 2080 2098 and comparing them with the available climate observations in order to assess the possible future variation in precipitation and temperature. The available stations observations were also used to derive monthly regressions between climate and topographic elevations to be adopted as a simple interpolation tool to estimate the spatial distribution of T and P in NIW. Changes in climate variables resulted significant for the near future only for T while in the distant future, both P and T showed respectively remarkable decrease and increase. These alterations will correspond to a decrease in snow covered area and anticipated snow melt thus altering the water balance of NIW both in terms of mean values and variability. To simulate the impacts on stream flow regimes, basin scale CCS were coupled with a conceptual water balance model named NIWaB that was previously developed and calibrated. A consistent module of the model was developed to capture the space time dynamics of the snow cover and snowmelt contribution. Such computations allowed to assess the possible climate change impacts on the hydrological signature of NIW which resulted strongly influenced by a shorter snowy period and a consequent enhanced seasonality of the river flows. The results may be helpful in assessing the opportunity of a new artificial reservoir as a strategy for climate change adaptation by enabling the storage of winter and spring flows as well as the regulation of flood peaks. Published version 1st CIGR Inter Regional Conference on Land and Water Challenges 10/09/2013 14/09/2013 Internazionale Contributo Contributo in atti di convegno ivan.portoghese PORTOGHESE IVAN michele.vurro VURRO MICHELE TA.P02.031.001 Impatto dei cambiamenti climatici sulla gestione delle risorse idriche |
