Volume:
Volume 3,
2010
Issue:
Issue 2 ,
2010,
September
Forecasting of Flash Floods Over Wadi Watier – Sinai Peninsula Using the Weather Research and Forecasting (WRF) Model
On Thursday, 1st of July, 2010. 11:16:44 AM
By Moustafa EL-Sammany
Topic: Other
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Citations: 10 |
Reads: 39 |
AbstractFlash floods are considered natural disasters that can cause casualties and demolishing of infra structures. The problem is that flash floods, particu read more
Flash floods are considered natural disasters that can cause casualties and demolishing of infra structures. The problem is that flash floods, particularly in arid and semi arid zones, take place in very short time. So, it is important to forecast flash floods earlier to its events with a lead time up to 48 hours to give early warning alert to avoid or minimize disasters. The flash flood took place over Wadi Watier - Sinai Peninsula, in October 24th, 2008, has been simulated, investigated and analyzed using the state of the art regional weather model. The Weather Research and Forecast (WRF) model, which is a reliable short term forecasting tool for precipitation events, has been utilized over the study area. The model results have been calibrated with the real data, for the same date and time, of the rainfall measurements recorded at Sorah gauging station. The WRF model forecasted total rainfall of 11.6 mm while the real measured one was 10.8 mm. The calibration shows significant consistency between WRF model and real measurements results. less
Effects of Drip Irrigation Water Amount on Crop Yield, Productivity and Efficiency of Water Use in Desert Regions in Egypt
On Thursday, 1st of July, 2010. 11:16:44 AM
By Hoda Soussa
Topic: Enviromental aspects of river engineering
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Citations: 15 |
Reads: 808 |
AbstractA surbsurface drip irrigation (SDI) system was used to investigate the appropriate irrigation water
schedules in open fields and greenhouse for diffe read more
A surbsurface drip irrigation (SDI) system was used to investigate the appropriate irrigation water
schedules in open fields and greenhouse for different vegetables. The study investigated and analyzed
different pipeline material, spacing between emitters, and soil profile. Also, it investigates the effects of
soil type and climate on water consumption. Two (2) Enviroscan sensors were installed to measure the
soil moisture. Also, two (2) weather stations were installed to measure the climate parameters. The
crop evapo-transpiration and the amount of irrigation water were determined using software based on
Penman–Monteith approach. The FAO guidelines were used as a reference. The obtained climate and
crop growth parameters were analyzed and the crop water use (which was simultaneously adjusted by
the moisture graphs of the Enviroscan) was determined. These determined values were used to develop
an appropriate schedule for water use and for crop production in order to ensure sustainable water
management. The results revealed that there was a significant increase in crop productivity by 18%
when the proposed SDI system is used over the normal drip irrigation system. less
Simulation of River Regulation Works to Improve Navigation Condition in Damietta Branch
On Thursday, 1st of July, 2010. 11:16:44 AM
By karima attia
Topic: River morphology
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Reads: 36 |
Downloaded: 2
AbstractDredging as a tool to enhance river transport in Damietta branch was conducted since 1999. About six
million meter cubic of bed material was removed read more
Dredging as a tool to enhance river transport in Damietta branch was conducted since 1999. About six
million meter cubic of bed material was removed with a total cost of 60 million Egyptian pounds. The
navigation channel has an average width of 40 m. However, the last 12 km of the route to Damietta
port is via an artificial canal of water depth of 4 m and channel width of 40 m at bed level which is
sufficient for two way traffic for container vessels. The waterway design specification has guaranteed a
minimum water depth for navigation of 2.3 m for uninterrupted period of 365 day a year. A navigation
hazard represented by a drop in the design water level was evident in 2006. The drop of water level
was threatening the satisfaction of 2.3 m water depth in some days within the year. This was attributed
that the channel carrying capacity was increased after the dredging process. This study aims at
improving the navigation condition downstream Zefta barrage, Damietta branch by installing
permanent regulation structure such as weirs. The weirs will enhance heading up of water in the weir
back water zone to solve some of navigational bottlenecks. A one dimensional mathematical model
(SOBEK) was used to simulate a study reach of 134 km downstream Zefta. Low discharge of 3
mm3/day is used as critical cases to represent a number of bottleneck locations of 165 and 75
respectively. The weirs are simulated in three locations according to the intensity of the bottlenecks.
Different crest level for the weirs is tested. The number of simulated cases is twelve. The model
enables the simulation of the hydraulic structures along the branch such as Zefta and Damietta
barrages. The study concluded that the weir installation has resulted in solving some of navigational
bottlenecks vary between 22 to 88%. The study recommended to combine between different regulation
work (dredging and weir installation) to get the best results from the economical point of view. Ship
transport activity can be put off when the required water depth is not available. Specific type of ships
with less draft can also be used during the hazard periods. The clearance can be less than 0.5 m
according to the environmental conditions and the number of ships in the waterway. less
Investigating the Environmental Impact of Power Plant Intakes and Outfalls Under Tidal Influence (Case Study: Suez Gulf-Egypt)
On Thursday, 1st of July, 2010. 11:16:44 AM
By mohamed mohamed abdel-latif mohamed
Topic: Enviromental aspects of river engineering
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Downloaded: 1
AbstractThis paper investigates the impact of the near and far field mixing zones in order to enhance the safe
environmental requirements under tidal influen read more
This paper investigates the impact of the near and far field mixing zones in order to enhance the safe
environmental requirements under tidal influence. A case study of a Power Plant located at the Suez
Gulf, Egypt was chosen for this investigation. Two physical hydraulic model studies were employed. A
near field undistorted physical model with a scale of 1: 50 that simulated the area close to the outfall
structure. A far field distorted physical scale model with a scale of 1:100 horizontally and 1:20
vertically that simulated the thermal plumes extension in the far field zone (away from the plant). A
recirculation of about 1.5oC occurred around the existing intake vicinity when the generating units were
operated with its full capacity during the low tidal level. The temperature distraction in the plant
vicinity complies with the aquatic environmental laws. The near field model revealed a riprap
protection in the vicinity of the outfall structure to protect the sea bed from erosion. The far-field model
revealed a minor recirculation at the inlet of a proposed intake structure. less
Inundations by High Releases Downstream High Aswan Dam
On Thursday, 1st of July, 2010. 11:16:44 AM
By karima attia
Topic: Flood Management
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Downloaded: 3
AbstractThe flood is a natural phenomenon defined as relatively high flow or stage in a river markedly higher
than the river carrying capacity. It occurs oft read more
The flood is a natural phenomenon defined as relatively high flow or stage in a river markedly higher
than the river carrying capacity. It occurs often quite frequently in almost all rivers in the world as a
result of a variety of causes. Aswan High Dam (AHD) represents a safeguard for Egypt against high
and low floods for more than fourty years. However, for dam protection and safety a planned releases
downstream the dam throughout the year should be applied to satisfy the dam operation rules (water
level upstream the dam in the first of Aug. =175.00 m). The planned releases may have downstream
impacts. Many problems for human properties and activities especially in the area of encroachment
were evident in 1998 for planned releases of 181 mm3/day downstream Assiut Barrages.
Rehabilitation, concepts and strategies are used by Egypt to adapt the main Nile and its two branches
for the planned high releases. The main purpose of this paper is to simulate 1998 flood and its impacts
on the reach located between Assiut and Delta Barrages. Mathematical model is used (HEC-RAS) to
predict the impact of different high releases. The model is calibrated by using 2003 hydrographic
survey data (one kilometer apart cross sections) together with maximum normal hydrological
parameters downstream Assiut barrages (discharge downstream Assiut of 171 mm3/day and water level
upstream delta barrage is 16.60m). Higher releases are simulated (200, 220, 250, 270, 300, and 350
mm3/day) to evaluate the impact on inundation process. Each release effect on land and infrastructure
inundations are analyzed and evaluated. Management lines concept is introduced as a rehabilitation tool
for land use management around the river. The main purpose is to secure the Nile against
encroachments. The study concluded that management lines should be implemented and tested in the
field. In addition, public awareness should be activated. less
Modelling of Sedimentation Upstream of Nyumba Ya Mungu Reservoir in Pangani River Basin
On Thursday, 1st of July, 2010. 11:16:44 AM
By Preksedis Marco Ndomba
Topic: GIS and Remote Sensing applications in river engineering
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Citations: 26 |
Reads: 89 |
Downloaded: 1
AbstractThis paper is reporting the preliminary findings of a research on modelling sedimentation in large
complex catchments. The study objectives were achi read more
This paper is reporting the preliminary findings of a research on modelling sedimentation in large
complex catchments. The study objectives were achieved by developing a conceptual framework. The
study case is a regulated Nyumba Ya Mungu (NYM) Reservoir catchment in the upstream of Pangani
River Basin (PRB) located in the North Eastern part of Tanzania. It should be noted that in literature
there are no compelling methods and tools for the purpose. The framework developed for this study,
therefore, comprised of a conceptual model and a network of sediment properties and yield fluxes
monitoring sites across the basin. The conceptual model was set up by linking a comprehensive
distributed, physics based, mathematical watershed model, Soil and Water Assessment Tool (SWAT),
and a set of rule based stepwise regressive models. Regression analysis was conducted under Data
Mining Tool (Cubist) environment. A sampling network embodies field measurements of upland
catchment erosion rates, continuous Suspended Sediment Concentrations (SSC) and Soil Organic
Matter (SOM) content sampling programme in the upstream major river tributaries and downstream
reservoir bathymetric survey. The feedback loop between the components of the conceptual framework
was developed and used. The study results suggest that modelling activities should be well guided by
analysis of field-based data in order to reduce the uncertainties involved in sedimentation studies.
Besides, the various components of the modelling framework must complement each other. This study
used one hydrological year sediment sampling programme data successfully to identify erosion
sources/ processes and predict long term annual average of NYM reservoir sedimentation rate. Testing
of the developed conceptual framework elsewhere is recommended. less
Investigation of Step Trends of the Nile River Flow Time Series
On Thursday, 1st of July, 2010. 11:16:44 AM
By Ageel Bushara
Topic: River morphology
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Citations: 6 |
Reads: 32 |
Downloaded: 1
AbstractHaving long-term daily-observed flow data of 44 years (1965-2009) makes a unique opportunity to
study the hydrological changes on the Nile basin due read more
Having long-term daily-observed flow data of 44 years (1965-2009) makes a unique opportunity to
study the hydrological changes on the Nile basin due to land use changes, upstream water usage, and
climate change, and to know their impacts on the Nile River flow. In this study, the annual flow time
series (TS), based on hydrological year (June- May), were analyzed and checked for the absence of step
trends using two statistical software: Freq (Zhou, 1992) and Spell-Stat (Agor and Librada, 2005).
Similar results were obtained.
Flow TS of the Nile, Blue Nile, and White Nile were analyzed for the flow observed at Dongola,
Eddeim (often written el Deim) and Khartoum, and Malakal stations, respectively. All flow TS were
tested for the absence of step trends by checking the TS for the stability of the mean and the stability of
the variance at 95% confidence level.
Pettitt test (change point test) was used to identify the possible step trends in the TS under
consideration. TS were checked for the absence of step trends for the probability higher than 0.8.
Results show that since 1987/1988, the Blue Nile flow has increased significantly, as observed at
Eddeim and Khartoum. For both Eddeim and Khartoum stations, the mean flow of the TS for the
period from 1965/1966 to 1986/1987 is statistical lower than the mean flow of the TS for the period
from 1987/1988 to 2008/2009. The flow increase after 1987/1988 creates step trend in the flow TS at
Eddeim and Khartoum. Flow TS at Eddeim and Khartoum were found to be both stable in the variance.
It is worth to mention that in 1988, Sudan had experienced huge and devastating flood (Sutcliffe et al.
1989).
On the contrary, the White Nile flow has decreased, as observed at Malakal. Since 1972/1973, the flow
has dropped significantly making the TS not stable in the mean. However, the flow TS is stable in the
variance.
Finally, the Nile flow TS, as observed at Dongola, was found to be stable in both the mean and the
variance, i.e., there is no step trend in the TS. Results also show that there are high correlations
between the stations on the Nile and the stations on the Blue Nile on one side and the stations on the
Attbra River on the other side, and a weak correlation between the stations on the Nile and the stations
on the White Nile. This indicates the strong influence of the Blue Nile and Attbra River flows on the
Nile flows. The implications of this study are for climate change studies, for water management and
planning, and for early warning systems. less
Integrated Flood and Drought Management for Sustainable Development in the Nzoia River Basin
On Thursday, 1st of July, 2010. 11:16:44 AM
By Simeon Dulo
Topic: Flood Management
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AbstractDirectives and policies increasingly call for more integrated management of land and water.
Frameworks such as integrated catchment management may ad read more
Directives and policies increasingly call for more integrated management of land and water.
Frameworks such as integrated catchment management may address these calls, and yet their
implementation requires decisions to be taken under conditions of extreme complexity and uncertainty.
This paper establishes a basis for managing flood hazards through an integrated community based
management protocol. It documents and assesses adoption/adaptation methodologies and past
indigenous knowledge for coping with floods and droughts. Through earlier SWAT catchment analysis
components of the Nile Basin Capacity Building Network (NBCBN) research, results from mapping
and zoning of flooding and drought events have been obtained. It is apparent in Nzoia catchment that
the areas under forest cover decreased markedly between 1970’s and 1986 from 1811.33 Km2 to
936.82 Km2. In contrast, the area under agricultural use is seen to have decreased over the years from
8433.85 Km2 in 1970’s to 6542.35 Km2 in 1980’s and to 5460.88 Km2 in 2000’s. A risk assessment
methodology and management plans for hazard prone communities have also been derived. Impacts of
floods and drought on the livelihood of the resident were also outlined. The report concludes with a
summary of mitigation and intervention strategies for the basins. The significant technical challenges
confronted in such an exercise may be overshadowed by the institutional challenges, including the
fundamental question as to whether organisations are truly committed. However, the reward for
overcoming such challenges is the opportunity to achieve genuine improvements in the social,
economic and environmental quality of our catchments. less
Impact of Land Use /Cover dynamics on Streamflow: A Case of Nzoia River Catchment, Kenya
On Thursday, 1st of July, 2010. 11:16:44 AM
By Charles Odira Maxwell
Topic: GIS and Remote Sensing applications in river engineering
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AbstractDegradation of watershed areas in Kenya’s basins is on the increase and is currently a major concern
for the government. The main causes of watersh read more
Degradation of watershed areas in Kenya’s basins is on the increase and is currently a major concern
for the government. The main causes of watershed degradation stem from the abuse and poor
management of forests and soils, overgrazing, extension of settlements into watershed areas, and
unsuitable felling of trees for fuel wood. Recent legislative reforms in the water and environmental
sector have been introduced to stem these environmental negative trends. However, extensive
quantitative hydrologic analysis is necessary for the assessment of the water balance of various basins
to form a basis for policy actions. In this regard, modelling the hydrologic cycle at a local scale still
remains the most important scientific method of research for the water balance assessment of basins.
The study area chosen in this study is the Nzoia basin in Kenya. This basin is a typical example of a
flood disaster prone basin experiencing increased flood related disasters due to the increased watershed
degradation in the recent past. The Nzoia basin is situated between latitudes 10 30’N and 00 05’S and
between longitudes 340E and 350 45’E and is the largest basin in Kenya’s Lake Victoria basin with an
approximate area of 12,709km2 and a length of 334km to its outfall into the lake. The Nzoia system has
its sources in the forested highlands (Mt. Elgon, Cherangani Hills, Nandi Hills and Kakamega forest).
The objective of this study is to simulate streamflow changes as a result of the land use/cover status as
at 1973, 1986 and 2000. Land use/cover data were based on Landsat images for these years. The
runoff response as a result of the observed land use/cover change was tested by keeping constant all
input datasets in a SWAT model and varying the land use. The results from the model showed that with
the expansion of the area under agriculture, the stream flow increases during the rainy seasons and
reduces during the dry seasons, whereas when the area under forest cover is increased the peak stream
flow reduces, but when the forest cover is reduced to almost zero there is an increased peak and mean
stream flow in the basin.
It is therefore worth noting that a decrease in surface runoff would be desirable, as this would also
decrease the devastating effects of floods; the rapid expansion of urban centres in the lower parts of the
catchment (Mumias, Bungoma, Rwambwa) can be said to be a major contributing factor to the annual
devastating floods. The results also indicated an increasing trend in rainfall amounts in parts of the
basin between the periods 1970 - 1998. A study of three rainfall stations (1BD02, 1DA02 and
1DD02A) has shown a significant increase in rainfall while one station, in the lower part of the
catchment (EE01), has shown a significant decrease.
The area under forest cover decreased between 1970’s and 1986 by 6.4% in the northwest and south of
the catchment. But between the 1980’s and the 2000’s there was an increase in area under forest cover
by 41.3%. Agricultural land use showed an increase in areal coverage between 1970’s and 1986 by
6.7%, but in the year 2000’s the agricultural activities declined by 4.6%. The area under
bushland/shrubland/riverine agriculture increased between the 1970’s, 1986 and the 2000’s by about
123.4% and 11.10% respectively. This could be as a result of an expansion in riverine agriculture. less
Assessing the Effect of Land Use Change on the Hydraulic Regime of Lake Awassa
On Thursday, 1st of July, 2010. 11:16:44 AM
By
Topic: Enviromental aspects of river engineering
Paper |
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AbstractFor the past years increases in population pressure, government policy and external influences have
caused a consistent change in the land cover of t read more
For the past years increases in population pressure, government policy and external influences have
caused a consistent change in the land cover of the Lake Awassa catchment. The change has come
about mainly due to deforestation as is the case in many other areas of Ethiopia. The effects of land
cover changes have had an impact on the water balance of the catchment by changing the magnitude
and pattern of runoff, peak flow and ground water levels. This study is mainly focused on the
assessment of the hydrological response of the catchment in relation to the land cover data of 1965 and
1998 using a Geographic information system (GIS) integrated with the hydrologic modeling. The result
of the remote sensing assessment on the land cover of the catchment indicated that natural vegetation
decreased by 11,768 ha or 9.06 % between years 1995-1998. This was mainly due to the expansion of
agriculture and urban area. Plantation expansion was 20,661 ha or 13.56 % and also urbanization
increased by 1,310 ha or 0.89 %. Based on these results, the inflow records were analysed statistically
to evaluate if changes in the land cover affected the hydrological response of the catchment. The results
of the analysis indicate that the average inflow to Lake Awassa in 1998 was 3.15 m3/sec or 99.34MCM,
whereas in scenario year 2017 the average inflow will be 3.5m3/s or 110.38MCM. So because of the
land cover change the flow will increase by 0.35 m3/s, that is, 11.04MCM. less
