Environmental Engineering Reference
In-Depth Information
A secondary performance indicator known as depleted fraction (DF), taken from
Kselik et al. (
2008
) was computed as
DF ¼ ET
act
=ðP
effect
þ SW
irrig
Þ
(13.12)
A DF value less than 1.0 would indicate that groundwater resources are not
required to supplement the precipitation and surface water supplies to meet crop
demands.
In addition to assessing irrigation water management for the study period, these
water balance and performance indicators should provide water managers and
decision-makers with data for long-term monitoring as water management
improvement measures are implemented.
13.6.2 Water Balance Analysis Results
All input data required for the monthly water balance analysis were prepared as
GIS-compatible files. A water balance analysis tool was developed to aid in
computing and visualizing results in both tabular and graphical form. Table
13.2
shows ET summaries by pilot sectors for each corresponding ORMVA. Figure
13.8
displays the annual data in graphical form.
Water balance results (Table
13.2
and Fig.
13.8
) display annual
ET
act
, effective
precipitation, surface water irrigation, and groundwater abstraction. The average
annual
ET
act
estimates for the Tadla sectors are more than 50% higher than for the
Haouz sectors and more than double those in the Doukkala sectors, based on a
weighted average over the total area of the investigated sectors within the
ORMVAs.
On an annual basis, the average unit volume of surface water available for the
investigated sectors in Tadla is 99% greater than the amount available for Haouz
and 78% greater than the amount available for Doukkala. This is consistent with,
and likely a contributor to, the lower
ET
act
reported above for these two sectors.
In addition, based on the water balance analysis results, the contribution of ground-
water resources (as evident in the values of
GW
abstract
and GW Indicator) is higher
for Tadla and Haouz than for the Doukkala sectors.
The weighted average annual GW Indicator is 30.5% for the sectors in Tadla,
36.7% for the sectors in Haouz, and
19.3% for the sectors in Doukkala. In terms of
DF, the weighted average annual value is 1.44 for the investigated sectors in Tadla,
1.63 for the sectors in Haouz, and 0.91 for the sectors in Doukkala. In Table
13.2
,
performance indicators are shown for each of the pilot sectors. DF value less than
1.0 for sectors would indicate that groundwater resources are not required to
supplement the precipitation and surface supplies to meet crop demands.
Extensive analysis was conducted for each of the irrigation sectors, including
water balance analysis providing groundwater recharge estimates where consumptive
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