TC Jordan: The Nationwide Groundwater Simulation Model
Report of the project:
Groundwater basins and transboundary aspects
Source: BGR
Background:
The Haschemite Kingdom of Jordan is divided up into three physiographic regions – highland, the Jordan Rift Valley and the desert – and is exposed to a combined Mediterranean and arid desert climate.
The country has a total area of 89,206 km2 and a population of 5.8 million (2005). The different climatic zones, and thus water-relevant living conditions, mean that most of the population are concentrated in a few conurbations, and particularly in the Amman-Zarqa region. 1.9 million people alone live in the greater Amman area. Because Jordan has one of the fastest growing populations in the world (approx. 3 %), the provision of adequate water supplies will continue to be a critical issue in future.
A global comparison identifies Jordan as one of the ten countries with the lowest volumes of available renewable water resources per capita. It has been suffering from a water crisis for many years. Although Jordan has the lowest water consumption per capita in the Near East – approx. 90 litres per capita per day – the country still uses more water than is naturally replenished by precipitation (groundwater recharge) and river water (the Jordan and Yarmuk). The non-renewable fossil groundwater reserves are now also being exploited to an increasing extent.
Because water demand is largely covered by extracting water from the renewable groundwater, this overexploitation causes considerable drops in the water table resulting in the drying out of wells and wetlands. The conflicting demands of the inhabitants, agriculture and industry are jeopardising the secure provision of water supplies nationwide, and also putting water quality at risk: this is because overexploitation causes salty water to encroach on the freshwater aquifers. In addition, the use of agricultural fertilisers and pesticides, and the partially uncontrolled disposal of waste and wastewater, also expose the groundwater to considerable pollution risks.
Objectives:
BGR’s co-operation projects with the Jordanian water authorities focus on the protection of water resources against contamination and overexploitation. BGR has contributed for approximately 30 years to the expansion of the relevant expertise, including the exploration and evaluation of groundwater resources throughout Jordan. The National Water Master Plan (NWMP) is the main planning instrument in Jordan for the sustainable use and protection of groundwater resources. BGR provides assistance in formulating the NWMP in the form of basic hydrogeological data and water balances. The water balances are calculated on an up-to-date basis from the nationwide groundwater simulation model jointly developed by BGR and the Ministry of Water and Irrigation (MWI).
Jordan’s groundwater system is part of a regional complex extending into the neighbouring countries of Syria, Iraq and Saudi Arabia. The groundwater system consists of a complex sequence of basalts, limestones and sandstones, which can be separated from one another by less permeable to almost impermeable rock formations consisting of marl, clay and schist. The groundwater system can be divided roughly into two flow systems. The upper system consisting of basalts and limestones is recharged by annual precipitation on the topographically high parts of the country, and develops a shallow dynamic groundwater system with natural local discharges and spring flow. Groundwater flow in this system is generally in the direction of the Wadi Sirhan topographical depression in the east of the country. The deeper system consisting of sandstone formations is filled with fossil groundwater which mainly accumulated several thousand years ago under the more favourable climatic conditions prevailing at the time (pluvial period). This groundwater generally flows in the direction of the depressions in the Jordan Valley and ultimately discharges into the Dead Sea, whose water level is approx. 400 m below global sea level. The local outcrops of the sandstone complex are only recharged in the northern part of the country; the large sandstone outcrops in the south of the country cover an area currently dominated by an arid climate where the aquifer is not recharged.
Presentation of project results
Source: BGR
Results:
The three-dimensional groundwater flow model covers an area of approx. 100,000 km2, encompassing ten hydrogeological units (rock formations) dipping down to depths of approx. 2,000 m. Parts of Saudi Arabia (Wadi Sirhan and areas south of the border of Jordan) were incorporated in the model for geohydraulic reasons – water knows no political boundaries.
Based on a groundwater situation calculated from the model assuming almost natural conditions, ideally not affected by abstraction activities, the model simulates the development of the groundwater system in Jordan over the last three decades making allowance for precipitation and volumes of groundwater abstraction.
The calibrated model developed on the basis of water level observations and discharge records is therefore the main instrument for modelling the current groundwater situation, and forecasting the effect of planned groundwater abstraction strategies. The potential effects are shown in the form of water level drawdowns and groundwater budgets (also for selected subzones, e.g. administrative regions and catchment areas). Two strategy scenarios have already been simulated with this model. These examples reflect the future planning of the NWMP and extrapolate the potential effects until 2050.
All of the water management measures change the groundwater system and can therefore have transboundary consequences. Large-scale activities therefore require pan-regional agreements and the exchange of information at an international level in order to avoid conflicts. The Wadi Sirhan area, the southern region of Jordan, and the basalt complex in the north around Jabal Arab in particular are all of high bilateral interest for joint management in this context.
Renewable groundwater resources
Source: BGR
Within the context of renewable groundwater reserves, there is a dramatic deficit between natural reserves and water consumption in the Jordanian water budget. Based on an average precipitation of 7 400 million m3 (MCM) for the period 1980 to 2004, annual average groundwater recharge has been 470 MCM. The extreme events of 700 and 185 MCM in 1988 and 1999 respectively clearly highlight Jordan’s dependence on annual precipitation.
The potential yield is supplemented in the northeast of the country by the transboundary groundwater inflow from the Syrian part of the basalt formation on the flanks of the Jabal Arab (68 MCM/year), and nationwide by an additional 42 MCM/year estimated in the model area from the return flow from agricultural irrigation.
From this total potential yield of 580 MCM/year (average), the groundwater system loses water naturally over the course of the year by way of e.g. spring flow. The natural groundwater discharge has reduced continuously from almost 400 MCM in 1980 to less than 300 MCM/year as a result of the general drawdown of the water table.
The remaining yield is much less than the annual groundwater abstraction from the renewable resources reservoir averaging 410 MCM. The overall balance therefore reveals an average annual deficit of 135 MCM (peaking at 400 MCM in the dry years 1999 and 2000). The annual deficit in the Amman-Zarqa conurbation alone is 50 to 70 MCM.
The future development of the groundwater system in Jordan was estimated from models inputted with different development scenarios. If overexploitation of the renewable groundwater continues, it is estimated that the additional regional drawdown of the groundwater level by 2019 will be around 5 to 10 m – with inevitable consequences for the environment.
Model results of production scenario 2
Source: BGR
The NWMP foresees changes in groundwater abstraction with the aim of avoiding these consequences. Further groundwater drawdown is to be slowed down and stopped in the long term by the step-wise modified reduction in abstraction rates of the renewable resources. This must be compensated for by harnessing other resources or possibilities: e.g. water savings in general (also in the agricultural sector by using improved irrigation techniques) and by increasing the abstraction of fossil groundwater which already accounts for 90 MCM per year.
Every year, approx. 200 MCM of fossil groundwater currently flows unused out of the sandstone complex into the Dead Sea in the form of natural depletion. Greater use of this water is planned and will give rise to regional drawdown of approx. 10 metres by 2019. The reduced inflow to the Dead Sea will also result in a lowering of its sea level which is already dropping continuously as a result of lower inflow from the Jordan River. Additional drawdown of the fossil groundwater by approx. 20 metres by 2050 will result from the planned intensive abstraction in the Disi area.
Literature:
SCHMIDT, G., SUBAH, A. & KHALIF, N. (2008): Model Investigations on the Groundwater System in Jordan - A Contribution to the Resources Management (National Water Master Plan). In: ZEREINI, F. & HÖTZL, H. [eds.]: Climatic Changes and Water Resources in the Middle East and North Africa; pp 347-359. Springer. doi: 10.1007/978-3-540-85047-2_22
