The Kabul times, Afghanistan Trustable News Agency.
Articles

Water resources of Afghanistan and related hazards under rapid climate warming

Parti II

A key challenge in water resources assessment for Afghanistan is the lack of longterm measurement of hydrometeorological variables, which hampers model-based projections at the catchment scale. The latter is a key scale for water resources and related hazard management. This lack of in situ data is especially challenging in areas strongly influenced by glacier melt because historical ice accumulation provides a “glacial subsidy” to streamflow until a glacier has become relatively small. In the absence of detailed information on incoming precipitation or on outgoing evapotranspiration, assessment of streamflow availability, dynamics and future evolution becomes challenging, and it is further complicated by groundwater storage dynamics. Here we review existing literature to summarize known climate change impacts on the cryosphere, streamflow, groundwater, and related hazards at the scale of Afghanistan, and complete this review with a small number of additional data analyses at local scales. We attempt to synthesize the existing knowledge to highlight knowledge gaps. Through the use of comprehensive search terms we have been able to identify 131 scientific papers and reports that relate to Afghanistan’s water resources, and we use these as the basis of our review. The review is organized as follows. We present: an introduction to the geographical and hydro-climatological context of Afghanistan; current knowledge and future projections for changing climate for the country; cryosphere processes in Afghan context analyses of streamflow data for glacierized and non-glacierized basins in Afghanistan; changes in groundwater, illustrated using data for Kabul city; the challenge of hydrological ex tremes; and a synthesis of this review and these data to argue that in Afghanistan, glacial subsidy may be hiding the effects of climate changes upon streamflow. Afghanistan is a mountainous country located in the subtropical zone, extending from 29°212 to 38°302 N latitude and from 60°312 to 75°E longitude. It has an arid and semi-arid continental climate, characterized by temperature and precipitation regimes characteristic of deserts, steppe and highlands. Precipitation primarily falls from winter storms that originate as Mediterranean cyclonic systems in winter and that move eastwards, generally affecting Afghanistan between November and April, and notably between January and March. The importance of Mediterranean storms for the lower mid-latitudes of Central Asia has been known for some time. In the summer season, monsoonal airflows associated with the Intertropical Convergence Zone (ITCZ) may also cross the border between Afghanistan and Pakistan causing occasional snowfall during summer in the highest mountain peaks in the northeastern region of the country. Figure 1. Geographical map of Afghanistan, showing elevation, river lines, hydro-meteorological stations, and glacier coverage, and identifying the four most glacier-covered regions. The subordinating map shows the provincial boundaries of Afghanistan. The lowland plains to the west and the north of the country experience low annual rainfall (~50–100 mm year”1) and extreme seasonal variations in temperature, with mean summer temperatures exceeding 33°C and mean winter temperatures of around 10°C. By comparison, the glaciated parts of river basins in the east receive substantially higher annual precipitation. This has traditionally fallen as snow between November and April, linked to the eastward movement of Mediterranean cyclonic systems, with mean winter temperatures below 0°C, and average summer temperatures not exceeding 15°C. The country is divided into five major river basins: (1) PanjAmu, (2) North, (3) Harrirud Murghab, (4) Helmand, and (5) Kabul. The elevation range of these basins is very large – from glaciated basins extending to over 7000 m a.s.l. in the Hindukush to non-glaciated basins lower than 250 m a.s.l. in the arid deserts in the South. These river basins make different contributions to the total volume of streamflow. Proportionally, the Panj-Amu and Kabul river basins produce the highest water volumes (38% and 35%, respectively) with respect to the total outgoing flow of Afghanistan despite having smaller basin area percentages (14% and 11% of the country). The other three basins have lower volumes than expected given their area, with 17% of the volume but 52% of the area for the Helmand River basin; 5.2% volume but 12% area for the Harrirud Murghab River basin; and 4.5% volume but 11% area for the Northern river basin. From: Hydrological Sciences Journal

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The Kabul times, Afghanistan Trustable News Agency.