Climate change impact is felt at a global scale. One of its results is the abnormal rain occurrence during monsoon season. In recent years, visible changes due to unusual weather events in Pakistan’s hydrological cycle were observed in the form of intensification of the hydrological cycle with changing of precipitation events such as floods and prolonged droughts. Hence, abnormal rainfall occurred in regions of southern and northern parts of Sindh, like torrential river floods (2010), flash floods (2011-2012), unpredictable rainstorms, etc. causing loss of lives, damaging infrastructures and crops, structures, and inhabitant displacement. In 2011, heavy cumulative precipitation has been recorded in the southern Sindh districts and the coastal belt of Badin and the LBOD and Kotri surface drainage system achieved their extreme heights. Another example of erratic rain occurred from September 8 to September 13, 2011 and produced an extraordinary discharge of about 14000 cusecs against the designed discharge of 4600 cusecs in the LBOD and Kotri surface drainage systems overtopping drains from several locations and wreaking havoc in the whole area of the southern part of Sindh.
The lakes of Sindh are in poor environmental condition due to the massive disposal of effluents. This paper presents the impact of water quality in Manchar Lake due to climate change and anthropogenic intervention. The lake is one of the biggest natural lakes in Sindh, Pakistan. The lake has three major sources of water supply: Indus River, hill torrents from the Khirthar Mountain range and the Right Bank Outfall Drain (RBOD-I)/Main Nara Valley Drain (MNVD). The water supply of the lake from the first two sources has been reduced due to morphological and climate changes. Hence, there is only one, and polluted, water supply to the lake, the RBOD-I/MNVD. At the same time, the use of poisonous materials for fishing has further contaminated the lake’s water. The RBOD system is connected with RBOD-III, RBOD-I/MNVD, Indus Link and RBOD-II on the right side of Indus River for safe disposal of wastewater into the Arabian Sea, which is still not functioning. Hence, more than 4500 cusecs of wastewater from the catchment area of RBOD have directly been discharged into the lake causing severe impact on flora, fauna and the livelihood of locals. In order to analyze the lake water quality impact, the water quality index (WQI) model was used. The results indicate that the water quality of four samples was very poor, while the fifth sample was unsuitable for drinking. The results of statistical analysis of parameters such as TDS, EC, SO4, Cl, Na, and hardness are higher to their permissible limits. Consequently, lake water possesses a high potential risk to local consumers and aquatic ecology.
This paper presents an assessment of groundwater quality and quantum in the command areas of two secondary canals in lower Sindh, the southern province of Pakistan. These canals off-take from Rohri main canal of Sukkur barrage in the Indus basin system. The scarcity of canal water is due to climate change, population growth and increased water demands. The farming community uses groundwater to meet the needs and improve their livelihood. The fresh groundwater in Sindh is only 22 percent, which is available in shallow aquifers underlain by salty groundwater of marine nature. The groundwater quality was assessed using electrical resistivity survey (ERS), which portrayed groundwater zones through 1D inversion software (IX1D) and geospatial tool inverse distance weighted (IDW). Four classes (fresh, marginal fresh, marginal saline, and highly saline) have been delineated at different depths from 25 to 150 m below ground surface. The groundwater aquifers are identified, and their quantum is estimated. The ERS results were also compared with the quality of collected water samples at various depths. The ERS results have identified fresh groundwater up to 40 m depth. The marginal quality groundwater could be utilized to increase crop productivity through conjunctive use with the canal water.
Sediment material transported by the Indus River has two origins, the catchment and its wetted perimeter, whereas the amount of materials transported from the river itself depends on variables such as the flow type and the sediment load. The annual sediment load transported in the Indus River ranged from 270 to 600 million tons (MT) before the building of dams and barrages. The average sediment load is 0.715 MT/day or approximately 260 MT/ year after the construction of hydraulic structures. The average particle size, D50, of the bedload is approximately 0.125mm at the Sukkur barrage [1]. In this study, research was conducted to evaluate sediment problems in the Nara Canal, take-off from the left pocket of the Sukkur Barrage on the Indus River. The collected data from the left pocket, the bed, and suspended material in upper Nara and its off-taking canals were analyzed to assess sediment transport dynamics of upper Nara canal at various locations and its off-taking canals. The bed material at RD 553+600 shows a minimum size of 0.07 and a maximum of 0.7mm with 54% fine-sand mixed with 46% medium-sand in 2003. Fine-sand increased to an average of 75% while medium sand diminished to 25% at RD 553+600 in Nara canal and at RD 595+000 in Jamrao complex in 2013. The suspended load with low and high flows during 2012 exhibits that in all the cases the sand proportion was increasing in the Upper Nara canal system flowing to the Jamrao complex. The sediment concentration value indicates that there is the deposition of sand at the upper Nara canal and the Jamrao complex causing a discharge reduction in the Nara Canal system.
Pinyari canal off-takes from the left bank of Kotri barrage with a design discharge of 13,636 cusecs which passes through the ridge of Hyderabad city along with New Fuleli Canal and Akram Wah on its left side. Its water is used for irrigation, agriculture, industrial, domestic, and drinking purposes in Hyderabad and Sajawal districts in Sindh. This canal is non-perennial. Water is being released with low discharge only for drinking purposes during the dry season and with full supply in the wet season. The global water quality issue reflects the major impact of socioeconomic development and population growth changes on freshwater resources including canals and rivers. This paper presents the impact of untreated wastewater disposal to the canal. The practice of disposing of untreated effluents has created serious health and environmental problems for the locals. The statistical and geospatial tool GIS has been used for the assessment of water quality with visualization of wastewater behavior in the canal. The results of the statistical analysis showed that pH was within the permissible limits but Electric Conductivity (EC), Total Dissolved Solids (TDS), Sodium (Na), and Hardness exceed them. The Water Quality Index of the samples rated from very poor to unsuitable for drinking, hence, canal water is unfit for domestic use or drinking purposes.
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