Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Diyala River

Indices-Based Evaluation of Spatiotemporal Distribution of Drought Within Derbendkhan Dam Watershed

Mahmoud Saleh Al-Khafaji; Rusul A.H. Al-Ameri

Engineering and Technology Journal, 2021, Volume 39, Issue 6, Pages 893-914
DOI: 10.30684/etj.v39i6.1802

Drought is one of the most significant natural disasters in Iraq. It has a strong impact on the water resources in Iraq. Consequently, it causes massive environmental damage, economic deficiency, and social problems to the country. Therefore, more considerations towards the study and management of drought has become of vital importance in recent decades.
In this paper, three drought indices (DIs) were computed for evaluation of the spatiotemporal of drought within Derbendikhan Dam Watershed (DDW) in the Diyala River Basin, Iraq. Based on the monthly weather data for the period (1984 – 2013) downloaded from the Climate Forecast System Reanalysis (CFSR) for eight stations located within DDW. The Reconnaissance Drought Index (RDI), standardized precipitation index (SPI) and Streamflow Drought Index (SDI) at 12-month time scale were computed to assess droughts in the DDW. For each index, the temporal variations of the drought severity and Drought Frequency Patterns (DFPs) for the period (1984 – 2013) were computed and analyzed. In addition, spatial distributions of the drought severity for each index were mapped and investigated. Accordingly, the DFPs were compared to specify the dominant and/or more frequent DFPs. The results show that the performances of different DIs are strongly correlated with the dominant factors of droughts and drought duration. Also, the SPI and SDI are less accurate than the RDI when both precipitation and evaporation are the main factors controlling the drought events. However, the SPI and SDI indices are identical in the same proportions of the dry years which are less than the ratio of dry years to an RDI, but the severity of the drought from the SDI results is higher than the severity of the drought relative to the SPIand RDI. The three indices indicate that the Eastern region is drier than the Western region, which is somewhat wet.

Impact of Climate Change on the Spatiotemporal Distribution of Stream Flow and Sediment Yield of Darbandikhan Watershed, Iraq

Mahmoud S. Al- Khafaji; Rana D. Al- Chalabi

Engineering and Technology Journal, 2020, Volume 38, Issue 2, Pages 265-276
DOI: 10.30684/etj.v38i2A.156

The impact of climate change on stream flow and sediment yield in Darbandikhan Watershed is an important challenge facing the water resources in Diyala River, Iraq. This impact was investigated using five Global Circulation Models (GCM) based climate change projection models from the A1B scenario of medium emission. The Soil and Water Assessment Tool (SWAT) was used to compute the temporal and spatial distribution of streamflow and sediment yield of the study area for the period 1984 to 2050. The daily-observed flow recorded in Darbandikhan Dam for the period from 1984 to 2013 was used as a base period for future projection. The initial results of SWAT were calibrated and validated using SUFI-2 of the SWAT-CUP program in daily time step considering the values of the Nash-Sutcliffe Efficiency (NSE) coefficient of determination (R2) as a Dual objective function. Results of NSE and R2 during the calibration (validation) periods were equal to 0.61 and 0.62(0.53 and 0.68), respectively. In addition, the average future prediction for the five climate models indicated that the average yearly flow and sediment yield in the watershed would decrease by about 49% and 44%, respectively, until the year 2050 compared with these of the base period from 1984 to 2013. Moreover, spatial analysis shows that 89.6 % and 90 % of stream flow and sediment come from the Iranian part of Darbandikhan watershed while the remaining small percent comes from Iraq, respectively. However, the middle and southern parts of Darbandikhan Watershed contribute by most of the stream flow of the watershed while the parts of lack land cover and steep slopes produce most the sediment.

Nitrogen Compounds Distribution in Diyala River Opposite Al-Rustimiyah Sewage Treatment Plants

Adnan A. Al-Samawi; Safaa N. H. Al-Hussaini

Engineering and Technology Journal, 2016, Volume 34, Issue 15, Pages 2971-2981

The reach of Diyala River just before its confluence with Tigris River south of the capital city Baghdad was taken as a case-study. This segment of Diyala River is exposed to multiple points of treated and raw municipal wastewater discharges of Al-Rustimiyah wastewater treatment plants. Its pollution status was assessed with regard to nitrogen compounds levels.
The aquatic parameters: DO, TN, TKN NH4-N, NH3-N, NO3-N, NO2-N, pH, and temperature were monitored and measured at nine sites along the river reach for a period of one year to assess seasonal variations. The first and last sites were chosen at the downstream and upstream of the points of pollution flowing into Diyala River, while the second to eighth sites were located at the effluents of the WWTPs of Al-Rustimiyah. It was found that water at sites two, seven, and four, respectively, were the most polluted points among all duo to the presence of the bypasses from the WWTPs at these sites.
With regard to NH4-N, NH3-N, and TN concentrations, the river was found to be heavily polluted with untreated wastewater at site two and between low to medium strength at other sites, except for site one. On the other hand, NO3-N and NO2-N concentrations categorized the river water as an effluent rather than a stream according to Iraqi standard classification.
Reversed relations were found between the DO concentrations and some of the nitrogen compounds and temperature. A statistical model relating TN concentration to DO, NH3-N, and temperature was derived. It was proved to be accurate.