1. Spatial and temporal drought analysis in the west bank
Introduced By:
Eng. Shadi Kalabani
Eng.Atyia Altos

2. Contents Introduction Literature Review Study Area Rainfall Analysis
Drought Analysis
Discussion and Conclusion
Recommendations

3. Drought definition
Consequence of reduction over extended period of time in amount of precipitation that is received.
usually over a season or more in length.
Lack of rainfall so great as so long.

4. Drought types
Metrological: Related to precipitation deficits which cause decreases in water supplies.
Hydrological: Resulted from low stream flows that directly affect established water uses under a given water resources management system.
Agriculture: Linked to crop failure as a consequence of decreases in soil moisture and has no reference to stream flow.

5. Research objectives
Study drought features and its effects in the West Bank.
Determine the spatial and temporal behavior of drought in the West Bank.
Determine the return periods of drought in the West Bank.
Predict the behavior of drought in future.

6. Literature review
Of drought

7. Literature review- introduction
There is a deep understanding and appreciation of the water scarcity problem in Palestine. This understanding led to actions and approaches to save water for its traditional uses.
The total current water use in the West Bank is estimated to be about (85m3/capita/year).
Agriculture continues to be the largest consumer of water accounting for more than 65 percent of total use.
The problem of drought makes this demand is very hard to get especially if it increases continuously.

8. Literature review- background
The rainfall of the West Bank is varying from station to station, thus because the topographic variation of the region.
Drought may affects specific locations more than others.
Most of the agriculture is in arid and semi-arid regions, and get water from a conveying systems, this classification of aridity is determined by aridity index.

9. Aridity index
The ratio of mean annual precipitation (P) to mean annual potential evapotranspiration (PET).
Any region considered to be:
Arid when 0.05≤P/PET≤0.2
Semi-Arid ≤P/PET≤0.5

10. Standardized Precipitation Index (SPI)
Meteorological drought is frequently described in terms of drought indices, which are convenient and relatively simple to use.
The SPI is a dimensionless index where negative values indicate drought and the positive values indicate wet conditions.

11. Standardized Precipitation Index (SPI)
Where, x : the mean annual rainfall xi: the annual rainfall at any year. σ : the standard variation.

12. Drought classification based on SPI
SPI value
Normal
≤-0.99
Moderate
-1.49≥SPI≥-1.00
Severe
-1.99≥SPI≥-1.5
Extreme
SPI≥-2.00

13. Drought effects
Drought is one the most damaging climate-related hazards. Drought is among the most multifaceted and least understood of all natural hazards
Affecting more people than any hazards.
hazardous phenomenon which can have sever impact on communities and water-dependant sectors.

14. Drought effects The many effects of drought can be listed as:
Economic : Retailers who provide goods and services to farmers must deal with reduced business. This later leads to unemployment and loss of tax revenue, also tourism sector.
Environmental: Losses are caused by damages to plant and animal.
Social: Impacts include health, public safety, conflicts between water users, and reduced quality of life.

15. Study Area
West Bank

16. Study area-introduction
The climate; temperature and precipitation vary with altitude, warm to hot summers, cool to mild winters.
The terrain mostly rugged dissected upland, some vegetation in west, but barren in east elevation extremes.
lowest point is the Dead Sea -408 m, and the highest point is Tall Asur 1,022 m over sea level.
The area of crops is about 18% of the total area.

17. Study area-Geography, Rainfall
Geography of the West Bank could be classified as landlocked; highlands are main recharge area.
Rainfall in the West Bank Ranges from 630 mm in mountains to about 140 mm in Jordan Valley and Dead sea.

18. Study area-Water resources
Water resources are either from Groundwater or springs.
amount of production of water is about 765 MCM/Year and it is generated in three categories:
-Groundwater: about 600 MCM able to be extracted from groundwater, 60 MCM of them is salty water.
-Running water which approximated of amount of (40-50) MCM
-Basically from Jordan River with amount of 115 MCM.

19. Study area-Water resources
The West Bank contains about 300 spring varies in quantity and quality.
The demand on water in West Bank which is about 160 MCM/Year (domestic and agricultural).
Covered by each of groundwater wells with percentage of 44%, springs 28 %, and the bought water from the Israeli company "Mecorot" with about 28%.

20. Study area- Climate, and Aridity
The climate of the West Bank is influenced by the Mediterranean climate Marked by long, hot, dry summer and short, cool, rainy winter.
The West Bank is relatively arid, with about 50% of the land having a rainfall less than 500 mm/year, including hyper-arid area with a rainfall less than 100 mm/year. However, the remaining land has a rainfall range of mm/year.

21. of five selected station
Rainfall Analysis
of five selected station

22. Rainfall analysis
Rainfall data is an essential element of basic data input to many hydrologic and engineering studies.
Peak rainfall data are used in designing storm water management systems and in determining the flooding potential of various storm events.
Monthly and seasonal data are used in determining supplementary irrigation water requirements, and in engineering studies related to storage analyses, water supply, reservoir management, and for drought management also.

23. Consistency analysis
In any rainfall analysis, study it is very important to check the consistency of the data after filling the missing data.
Double mass curve technique was used to assess the internal consistency of the rainfall data.
The following figure shows the result of consistency analysis for the five selected stations.

24. Consistency analysis

25. Rainfall analysis-spatial distribution
The West Bank is characterized as a arid to semi-arid region with rainfall varies spatially from one station to another and temporally at specific station on many factors.
Five rainfall stations will be used to characterize the drought feature in the WB. These stations are located in, Jericho, Hebron, Jenin, Tulkarm, and Nablus.
The reason for choosing these stations is their geographic distribution, and the availability of data for more than 30- years.
The following map shows the spatial distribution of average rainfall in West Bank.

26. Spatial distribution of rainfall

27. Rainfall analysis-temporal variation
All hydrological variables can be considered as functions of time.
The short term, the temporal variation is influenced by the day-to-day weather systems.
In the medium term, the variations are influenced by seasonal climatic conditions.
In the long term, the variations are often not clearly defined and it is difficult to attribute such variations to a single causative factor.
In this study, emphasis is placed upon the medium and long term temporal variations when the hydrological variable is considered as a time series of monthly and annual data.

28. Temporal variation- annual rainfall analysis
To understand the temporal variation of West Bank rain stations we will show the figures for Jericho and Nablus station.
The following figures clarify the time-annual rainfall relationship for the two stations.

29. Mean annual rainfall for Jericho station

30. Mean annual rainfall for Nablus station

31. Rainfall analysis- Monthly
The mean monthly rainfall for the records of the five stations was calculated for the period from 1976 to 2008.
It was difficult to find the monthly data for Jenin station because it is contained many of missing monthly records that could not be estimated using hydrological methods.
The following graph summarizes the results temporal variation of monthly averages data.

32. Temporal variation of monthly data

33. Monthly rainfall analysis
The wet period for the WB continues from Oct to May, all maximum values were in January.
Hebron station had the maximum average of the four stations.
The rainfall regime of the four stations was approximately the same.
The shape of the graphs for all stations was similar. Most of monthly rainfall was in January.
From the monthly rainfall (by percent) table, it is clear that approximately 25% of the rain falls in January for all stations. And February comes next with approximately 21%.

34. Rainfall analysis- Trend analysis
Simple trend analysis of the 5-years moving average is applied to the available annual rainfall data of the five stations.
This procedure of 5-year moving average depends on calculating the average of each adjacent five years.
The following figures show the results, next to them a table summarizes the equation of the best fit line (first order).

35. Trend analysis

36. Trend analysis

37. Trend equation: Y=(b X +a)
Trend analysis
Rainfall station
Trend equation: Y=(b X +a)
Jericho
0.361x
Hebron
3.1779x
Nablus
0.5051x
Tulkarm
-1.732x
Jenin
0.1409x

38. Rainfall analysis- frequency
The frequency of hydrologic event is the probability that some value of discrete variables will occur or some value of a continuous variable will be equaled or exceeded in any given year.
Straightforward plotting technique was used to obtain the cumulative distribution, the other method uses frequency factors.
Following figures represents the return period of specific rainfall values, and exceedance probability for Hebron station.

39. Return period

40. Probability of exceedance/non-exceedance

41. Drought analysis
Spatial and temporal

42. Drought analysis-introduction
Drought is one of the most damaging climate-related hazards. Drought is among the most multifaceted and least understood of all natural hazards.
Can have severe impact on communities and water- dependent sectors.
Difficult to predict.
Drought is defined based on some deficiency of precipitation that results in water shortage for some activity related to use of water.

43. Drought analysis-introduction
Precipitation is the primary factor of drought occurrence; nevertheless, other factors like wind, temperature, and relative humidity have strong effects of increasing the severity of drought.
The first affected by drought is the agriculture through decreasing of moisture in the soil and increasing the evapotranspiration.
The severity of drought depends on the moisture deficiency of the soil, the duration of this deficiency, and the extent of drought area.
Drought variation in the West Bank has been investigated using SPI which identified previously.

44. Drought analysis-background
The temperature in West Bank has risen significantly over the years of the twentieth century; this increase was not uniform at all in the last decade of the last century.
In general, heat waves have become more severe and longer than ever before.
The occupied Palestinian territories and its neighbors in the Mediterranean basin faced a turbulent rain and flooding, and were not familiar with these events in the past.
The rise in the intensity of rainfall, coupled with low ratio of total precipitation will inevitably lead to erosion surface, which increases in the process of soil erosion and salination.

45. Drought analysis based on SPI
The SPI was calculated for the last 30-years in the West Bank of study and it was found that 19 out of 30 years there is drought.
Normal drought is the most frequent of years, but there was an occurrence for moderate drought along several years, and severe drought for few years.
The following contour map represents the maximum SPI values based one the five selected stations.

46. Drought map- Maximum values of SPI

47. Drought frequency
The following table indicates the frequency of each drought class.
Drought Frequency
Drought Category
Jericho
Hebron
Nablus
Jenin
Tulkarm
Normal Drought 14 13 18
Moderate Drought 3 4 6 5
Severe Drought 2 1
Sum 19 21

48. Drought analysis-Spatial distribution
The changing in drought values along West Bank must be correlated with spatial distribution and values of rainfall.
The maximum drought values equal the minimum rainfall value minus the average rainfall of specific station.
Maximum drought=Deficit=Min. Rainfall- Average Rainfall
The following map represents the spatial distribution of maximum drought (deficit) values.

49. Spatial distribution of maximum drought

50. Conclusions and Recommendations

51. Conclusions
Droughts are generally perceived to be a prolonged period with significantly lower precipitation related to normal level.
Most of formulas of drought prediction are based on statistical analysis, because drought is treated as random and probability is the main way to deal with.
In West Bank there is a variation in rainfall at the various stations all over the area, and this is because of the variation in classification of areas .
Drought produces a large number of impacts in the West Bank that affects the social, environmental, and economical standard of living.

52. Conclusions
In the West Bank, annual average rainfall varies between 630 mm falling on the mountains of Nablus, Jerusalem and Hebron to 140 mm in the Jordan valley and around the Dead Sea.
The West Bank water resources are very limited and all either from Groundwater or springs.
The rainfall regime of the five stations was approximately the same in both monthly and annual data.

53. Conclusions
Based on SPI values the drought classification in the West Bank ranges from normal to severe droughts. Normal drought was the most frequent. The maximum drought occurred in 1999.
Both of spatial distribution of rainfall and maximum drought were varied from stations to another.

54. Recommendations
Manage the water resources in such away that reduce the drought consequences.
Try to find new water resources to fulfill the increasing demand.
Study and analyze all West Bank rainfall stations to make deep understanding of spatial and temporal behavior of drought.
From political side view, Palestinian Authority should raise the problem of absolute and unfair Israeli’s control over the Palestinian water resources.

55. Recommendations
Make more spatial and temporal analysis on the other factors that affecting drought (e.g. temperature, humidity, and topography).
Support the sector of agriculture because it is the most affected by drought conditions (e.g. design systems for irrigation and drainage), specially the areas of maximum potential drought.
Municipalities of West Bank have to aware people of the importance of water saving techniques.
Construct wastewater treatment plants and use the effluent for agriculture practices.

56. THANK YOU AND SPECIAL THANKS TO DR.SAMEER SHADEED
ANY QUESTION?????
THANK YOU AND SPECIAL THANKS TO DR.SAMEER SHADEED