The Indus Plains of Pakistan are situated in arid to semi-arid climate where monsoon rains are erratic and mostly fall in the months of July and August. These rains are not only insufficient to grow even a single crop without artificial irrigation but also cause flood havoc very frequently that is associated with the climate change. The Indus river transports water for agriculture, industry and domestic usage within the basin and downstream. The Indus Basin is among the few basins severely affected by global warming and resulting climate change. The alteration in temporal and spatial patterns of rainfall has resulted in unexpected drought and floods. About 70 to 80% of total river flows occur in summer season due to snow melt and monsoonal rainfalls. Lack of storage reservoirs has decreased the ability to regulate flood water as well as its potential use during the drought season along with cheap hydro-electricity generation. The sedimentation in the system has limited the storage capacity of the existing three reservoirs by 28%. Consequently carry over capacity of these storage structures is only 30 days compared to 120 to 220 days in India and 900 days in Colorado Basin. Pakistan is facing shortage of good quality water due to competition among agricultural and non-agricultural sectors, this scenario will continue rather will further aggravate in future. According to the climate change scenario, the warming is reflected in the river-flow data of Pakistan, especially during the past 2-3 decades. To bridge the gap between fresh water availability and demand, ground water is being pumped to meet the irrigation requirements of crops. The pumped ground water (70-80%) is brackish and could become a sustainability issue in the long run. The prolonged agricultural uses of such water will deteriorate soils, crops and human living environments. Water quality parameters usually considered include electrical conductivity (EC) for total soluble salts, and sodium adsorption ratio (SAR) and residual sodium carbonate (RSC) reflect the sodicity hazards. In order to limit or even to eliminate adverse effects of such waters, certain treatment and/or management options are considered as important pre-requisites. For bringing down high concentration of total soluble salts, dilution with good quality water is the doable practice. To decrease high SAR of irrigation water, a source of calcium is needed, dilution (with good quality water) will decrease SAR by the square root times of the dilution factor, while use of acids will be cost-intensive rather may adversely impact the soil health. For high RSC, dilution with low CO32-+HCO3- water will serve the purpose, addition of Ca-salts will raise Ca2++Mg2+ to bring a decrease in water RSC, while acids will neutralize CO32-+HCO3- to lower water RSC. Gypsum is the most economical and safe amendment while acids could also decrease RSC but at higher relative cost. City wastewater and seed priming in aerated gypsum solution is also presented. Such practices at small and/or large scale surely will help a lot to sustain the food security and the environment in the days to come where climate change has to be experienced round the world. Therefore, a well-coordinated program is necessary to create awareness among different sections of the society including the policy makers, general public, organizations, industrialists and farmers.
TopIntroduction
The Indus Plains of Pakistan are situated in arid to semi-arid climate zones where rains during monsoon are erratic and mostly fall during the months of July to September. These rains cause flood havoc very frequently that is associated with the climate change; floods during the years of 2010, 2011 and 2014 are very good examples to such climate change impacts those resulted in hundreds of human and animal deaths as well as caused billion dollar loss to infrastructures, soil quality and crops. The Indus river transports water for agriculture, industry and domestic usage within the basin and downstream. About 70 to 80% of total river flows occur in summer due to snow melt and monsoonal rains.
The effect of climate change is not limited to water availability only but it also affects crop yields and thus the food security and worsens the human living environments. The increasing soil salinity might cause additional harm in future, if less annual rainfall and higher temperatures prevailed at the current rate in future due to climate change. Due to reduction in annual rainfall, sufficient leaching of salts will not be achieved and higher temperatures will further aggravate the salt stress in regions already threatened by soil salinity (Sommer et al., 2013). The availability of water in Pakistan has decreased from 5300 m3/year/person in 1950’s to 1066 m3/person/year in 2010 and it is estimated to be < 850 m3 per capita by the year 2025 (WAPDA, 2011). The World Bank has included Pakistan in the list of 17 countries predicted to encounter severe water shortages by 2025. There is immense need and scope to develop additional surface water storage for drought periods since a plenty of river water is discharging into the Arabian Sea, ≈ about 34 to 37 million acre foot (MAF) water is discharged into the sea. Such policy issues have to be decided by overlooking the political interests and giving priority to national interests by all the sections of society including politicians, policy makers and techno-crates.
An additional option is ground water (unfortunately poor quality) that may supplement growing irrigation needs because of increased cropping intensity and competition for fresh water by non–agricultural sectors. At present, > 1.07 × 106 tube wells are pumping 9.05 × 106 ha–m ground water in Pakistan (Federal Bureau of Statistics, 2011-12), of which≈ 70-80% is unfit for agriculture because of high EC, SAR and/or RSC (Ghafoor et al., 2004). The irrigation with poor quality water may cause soil salinity/sodicity, poor infiltration, hard setting of soils, specific ion toxicity in plants; all combined to adversely affect the growth and economic yields of crops along with human living environments. Further to this, sub-soil drying due to draw-down of water table could be an important future concern (Wichelns and Qadir, 2015).
The ground water, storm water during floods and raw city sewage (from industry-mix) may pose serious hazards because of high EC (≥1.0 dS m-1), SAR (≥10.0), RSC (≥2.5 mmolc L-1), heavy metals, high Mg to Ca ratio, diseases, pathogens, detergents, azo-dyes and pesticide residues (Murtaza et al., 2010; Qadir et al., 2010). However, management or treatment depends upon many factors like crop type, plant growth stage, physical/chemical properties of soils, and reactions between water and soil solids, climatic factors, farmers’ skills, drainage water quality, requirements of consumers and socio-economic conditions and acceptable decrease in produce yield as well as quality. Recently United Nations Climate Change Conference (COP21, 2015) was held in Paris ended up with the conclusions to decrease global greenhouse gases (GHGs) emission to zero level and to limit the average rise in global temperature to 2 degrees Celsius. To follow the goals and accomplish them saline water can be used for irrigation to bring more lands under cultivation. Bio saline agriculture can help in improving salt-affected soils such as cultivation of salt tolerant crops and growing of forest trees in barren lands instead of leaving them fallow. This would help in sequestering environmental CO2 and alleviates global temperature rise. Deserts can also be made productive by installing solar energy panels. Recently, Morocco has floated a tender for 400 MW solar power project (COP21, 2015). In Pakistan a solar power project has also been installed in Bahawalpur with a capacity of 100 MW.