Ilyas Masih

Shatt al Arab River system under escalating pressure: a preliminary exploration of the issues and options for mitigation

ABSTRACT This paper provides a broad description of the current state of hydrological and geographical characteristics of the Shatt al Arab River (SAR), and analyses the severe decline in water quantity and escalating levels of salinity. The analyses cover SAR as well as all contributing rivers and Mesopotamian Marshlands, which is essential to present a holistic picture of the issues. The analyses are based on the most recent data, though limited, on water availability, water resources development and management infrastructure, and water quality status. The study shows that the water inflows have significantly reduced and the water quality status has deteriorated to alarmingly high levels, especially from Basra to the river mouth. The crisis can only be averted through the cooperative water management initiatives taken by all the riparian countries, which require a paradigm shift from the current approach of unilateral water management planning to international cooperation and management on the shared water resources. The crisis mitigation strategies should find ways of increasing inflows and improving water quality from the upstream source rivers. At the same time, local measures are required to avoid drainage of poor-quality domestic and industrial effluents and highly saline water from the marshes into the SAR. These efforts should be supported by sound scientific information, which is also limited at the moment.

Anthropogenic and tidal influences on salinity levels of the Shatt al-Arab River, Basra, Iraq

ABSTRACT Understanding the salinity variation caused by a combination of anthropogenic and marine sources is important for water resource management in heavily used rivers impacted by tidal influence. A quantitative analysis of intra-annual variability of salinity levels was conducted in the Shatt al-Arab River. Based on hourly records during 2014, the results showed high spatiotemporal variability in the range of 0.2–40.0 ppt. Similarities in salinity dynamics were used to divide the river course into four distinct spatial units to guide respective management actions. Salinity dynamics are influenced by different sources of saline water inflows and withdrawals associated with irrigation, industrial and municipal waste, marshes and by seawater intrusion. Adapting a simple interpolation approach, the measured distance of seawater intrusion was 80 km upstream the river mouth. Continuous monitoring of water quality can localize and assess the relative impact of the various salinity sources at different times. Managing seawater intrusion and any local effects should take into account variations in quantity and quality of irrigation return flows and wastewater discharges.

Impact of reservoir operation and climate change on the hydrological regime of the Sesan and Srepok Rivers in the Lower Mekong Basin

The transboundary Sesan and Srepok sub-basins (2S) are the “hot-spot” areas for reservoir development in the Lower Mekong region, with 12 reservoirs built in the Vietnam territory. This study examines the impacts of reservoir operations in Vietnam and projected climate change on the downstream hydrologic regime of the 2S Rivers by jointly applying the Soil Water Assessment Tool (SWAT) and Water Evaluation and Planning (WEAP) models. Different scenarios of reservoir operation are considered and simulated to assess their impact on annual, seasonal, and monthly flow regimes under maximum hydropower capacity generation with and without taking into account the minimum flow requirement downstream near the Vietnam border with Cambodia. The precipitation and temperature projections from the high-resolution regional climate model HadGEM3-RA under two Representative Concentration Pathways, 4.5 and 8.5, of HadGEM2-AO are used as future climate change scenarios for the impact assessment. The study results show that reservoir operation leads to an increase in the dry season stream flows and a decrease in the wet season stream flows. The monthly flow regime exhibits considerable changes for both the Sesan and Srepok Rivers but with different magnitudes and patterns of increase and decrease. Climate change is likely to induce considerable changes in stream flows, though these changes are comparatively lower than those caused by reservoir operation. Climate change is likely to have both counterbalancing and reinforcing effects over the impact of reservoir operation, reducing changes during dry season but increasing changes in most of the other months.

Supporting well-informed decision and policy making through hydrological data analysis and modelling: the case of the Karkheh Basin, Iran

This paper shows how hydrological analysis and modelling can help guide water policy in the Karkheh Basin, Iran. The study suggests that water development strategy should take into account the high variability of the water resources, including declining low flows and intensification of floods in different parts of the basin. The modelling results suggest the promotion of soil and water conservation interventions due to their minimal impact on downstream flows. Conversion of rain-fed areas to irrigation may cause severe reduction in monthly flows. Therefore, only partial development is recommended, about 0.1 million ha out of a potential 0.5 million ha.

Hydrograph separation using tracers and digital filters to quantify runoff components in a semi-arid mesoscale catchment

1 IHE, Delft, The Netherlands University of KwaZulu‐Natal, Centre for Water Resources Research, Pietermaritzburg, South Africa Section of Water Resources, Delft University of Technology, Delft, The Netherlands UN World Water Assessment Programme (WWAP), UNESCO, Perugia, Italy Umgeni Water Chair of Water Resources Management, University of KwaZulu‐Natal, Pietermaritzburg, South Africa Correspondence Aline Maraci Lopes Saraiva Okello, IHE, Delft, The Netherlands. Email: a.saraiva@un‐ihe.org

Analysis of Possible Actions to Manage the Longitudinal Changes of Water Salinity in a Tidal River

In previous studies we have ascertained that inflows and seawater intrusion in the Shatt al-Arab River (SAR) are two key physical factors behind fluctuating and sharply escalating salinities observed in recent years. Such levels require a series of countermeasures and investigative studies to translate physical factors into a salinity dynamics model to understand the problem and its impact as these factors vary in location, time and quantity. A one-dimensional hydrodynamic and salt intrusion numerical model was applied to simulate the complex salinity regime in the SAR based on hourly time-series data for the year 2014. The model was used to analyse the impact of different management scenarios on salinity under different conditions. The results show a high correlation between seawater intrusion and river discharge. Increased use of water upstream and local water withdrawals along the SAR will increase seawater intrusion and salinity concentrations. Improving the quantity and quality of the upstream freshwater sources could reduce salinity levels. Discharging the drainage water into the river could be used to counteract the salt intrusion, considering that its location affects both the salinity distribution and extent. A scenario analysis based on a numerical model constructed for the longitudinal salinity variation associated with different sources in a tidal regime, can efficiently screen alternative water management strategies.

An exploration of disinfection by-products formation and governing factors in chlorinated swimming pool water

This paper investigates disinfection by-products (DBPs) formation and their relationship with governing factors in chlorinated swimming pools. The study compares concentrations of DBPs with WHO guidelines for drinking water quality recommended to screen swimming pool water quality. The statistical analysis is based on a global database of 188 swimming pools accumulated from 42 peer-reviewed journal publications from 16 countries. The mean and standard deviation of dichloroacetic acid and trichloroacetic acid were estimated as 282 ± 437 and 326 ± 517 μg L-1, respectively, which most often surpassed the WHO guidelines. Similarly, more than half of the examined pools had higher values of chloral hydrate (102 ± 128 μg L-1). The concentration of total chloramines (650 ± 490 μg L-1) was well above the WHO guidelines in all reported cases. Nevertheless, the reported values remained below the guidelines for most of the studied pools in the case of total trihalomethanes (134 ± 160 μg L-1), dichloroacetonitrile (12 ± 12 μg L-1) and dibromoacetonitrile (8 ± 11 μg L-1). Total organic carbon, free residual chlorine, temperature, pH, total nitrogen and bromide ions play a pivotal role in DBPs formation processes. Therefore, proper management of these governing factors could significantly reduce DBPs formation, thereby, contributing towards a healthy swimming pool environment.