**1. Introduction**

Pakistan is the fifth most populous and developing economy, with a population of over 22.50 million. The world's best irrigation system lies in Pakistan and 80% of the country's population lives in the Indus Basin. Despite this, Pakistan has become a water-stressed country and, as per the estimates of the United Nations (UN), the availability of per capita water in Pakistan is 1090 m<sup>3</sup> [1,2]. The agricultural sector has been the key contributor towards the economic developments of the country since it achieved independence. The contribution of the agricultural sector to GDP of Pakistan during FY 2021–22 was around 22.7%, comprising 37.4% of the labor force [3]. The agricultural sector and water resources are under immense pressure, as the population of the country is increasing 2.6% [4]. The increasing population demands more food, which requires more areas to be cultivated. The Pakistan Council of Research in Water Resources (PCRWR) have intimated that a water shortage is expected by 2025 if no new water reserves are constructed. Farmers are fulfilling their agricultural water needs by overexploiting ground water. The poor quality of ground water is resulting in salinization, which is an alarming concern for

**Citation:** Zahra, S.M.; Shahid, M.A.; Misaal, M.A.; Zaman, M.; Imran, M.; Azam, S.; Hussain, F. Sustainable Water Management in Indus Basin and Vulnerability Due to Climate Change. *Environ. Sci. Proc.* **2023**, *25*, 36. https://doi.org/10.3390/ ECWS-7-14203

Academic Editor: Luis Garrote

Published: 14 March 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

sustainability of agriculture in Pakistan [3]. Pakistan is among the list of countries which are significantly affected by salinity. Conjunctive managemen<sup>t</sup> practices of ground and surface water can increase the irrigation effectiveness and efficiency [4]. About 70% of irrigated plains are using ground and surface water simultaneously. With the growing economy, the distribution and managemen<sup>t</sup> of irrigation waterways is a serious concern for the future. The municipal and industrial supplies in urban areas are predicted to reach 14 km<sup>3</sup> from 5.3 km<sup>3</sup> by 2025 [1] and per capita water availability will be reduced by 32%, resulting in a food shortage of 70 million tons [5]. The Indus Basin was designed to supply low-intensity irrigation in large areas of canal command. The increase in cropping intensity is increasing the gap in supply demand and creating incessant unrest.

Climate change is one of the worst developments of that century, and has significantly affected water supply and cropping patterns. Glacial melt and retreat, change in precipitation patterns, and snow melt are the most frequently observed uncertainties resulting from climate change. About 45% of basin flow is generated by snow and glacial melt, which indicates that vulnerability to climate change is very high. The Hindu Kush Himalaya (HKH) range is widespread over 2000 km<sup>2</sup> in the Asian continent and contains rivers such as the Brahmaputra, Indus, and Ganges. Almost 1 billion people in Nepal, India, Bangladesh, Pakistan, China, and Bhutan are dependent on these rivers. Recent studies have predicted that glacial melt will be increased due to global warming, which can increase the river flows by 40% [6], but the average flow rates will be decreased by 60% in Indus Basin [7]. The duration between May and September accounts for 85% of discharge in the Indus Basin in form of snow and glacial melt and monsoon activity. The hydrological cycles are expected to change, as the floods of 2010 and 2022 are examples of a hydrological system [8]. Therefore, there is a need to adopt and implement water managemen<sup>t</sup> techniques, the building of new reservoirs for water storage, and the allocation of water resources in an optimum way. Additionally, mitigation measures are needed to tackle the effects of climate change to ensure water and food security and safety in Pakistan.

### **2. Materials and Methods**

### *2.1. Study Area*

The area of the Indus Basin is 566,000 km<sup>2</sup> and spread over four provinces of Pakistan, i.e., Punjab, Khyber Pakhtunkhwa, Baluchistan, and Sindh. The basin length of Indus is about 2900 km. It is fed by the eastern (Sutlej and Ravi) and the western (Chenab, Kabul, and Ravi) rivers, as shown in Figure 1. The river flows through an elevation of 18,000 ft from the Himalayas to the plains of Sindh and discharges into the Arabian Sea. The Indus Basin in Pakistan has a mean annual flow of 176 billion m<sup>3</sup> and 90% of the flow is used for irrigation purposes. The irrigation network consists of the main, branch canal, and distributaries with a length of about 57,000 km, with 88,600 outlets.

**Figure 1.** Digital elevation model of Indus Basin with dams, rivers, and flood-affected areas.

### *2.2. Data Collection and Analysis*

Pakistan is one of the most climatically varied countries due to its wide temperature range, which includes extremes such as the Sahara desert's temperature and the arctic cold of Alaska. Data on extreme events of climatic parameters, i.e., temperature and precipitation, were collected for the duration of 1919–2022. The data were collected from the World Meteorological Organization (WMO) [9] and Pakistan Meteorological Department (PMD) [10]. The collected data were processed in GIS to highlight the main areas in which extreme events occurred. As per the intensity of extreme events, the hot spotted areas were graded using Inverse Distance Weighing (IDW) method.

### **3. Results and Discussion**

### *3.1. Sustainability of Water*

Pakistan is the fifth most populous country in the world, with a population growth rate of 2.6%; its population is expected to reach 250 million by 2025 [4]. The urban population of Pakistan comprised 37% of the country's population in 2017, and this is expected to reach 52% by 2025 [5]. The movement of the population towards cities will increase water consumption by 8%. The per capita water availability in Pakistan was 5000 m<sup>3</sup> in 1947, which was reduced to 1100 m<sup>3</sup> in 2005 and is predicted to drop to 800 m<sup>3</sup> by 2025 [5]. According to the estimates of the UN, the water demand in Pakistan is increasing by 10% per annum. The area-wise water withdrawal in Pakistan is calculated as 175 km3, of which around 71% (124.25 km) is from surface water and 29% (50.75 km) is from groundwater [8]. In Pakistan, surface water has always been a burning topic, but groundwater has also many problems associated with it, i.e., salinity, overdraft, and waterlogging. According to an estimate, there are 0.8 million pumps installed in Pakistan and 50% of agricultural water needs in Punjab are met by them. The over-pumping of groundwater has led to the salinization of 4.5 million hectares; about 50% of the area lies in irrigated plains of the Indus Basin. The inappropriate irrigation practices and waterlogging due to seepage from unaligned canals have affected nearly 1 million hectares of irrigated plain of the Indus Basin, but the problem of salinity is worse in Sindh. The curative measure was taken to counter the problem of salinity, but proved to be futile, and the land productivity badly decreased. The water storage capacity of Pakistan is considerably lower than that of developed countries. The per capita water availability in US and China is 5000 and 2000 m3, respectively, while it is 150 m<sup>3</sup> in Pakistan [1]. The storage capacity of Pakistan is only 30 days, while our neighboring country India has 120 to 220 days. The maximum storage capacity of water, i.e., 900 days. The storage capacity of any country depends upon its reservoirs. Pakistan has only two main reservoirs, i.e., Tarbela and Mangla, and the capacity of both reservoirs has been reduced by 20 and 32% due to sedimentation [5]. The Lieftinck report of 1968 stated that one Tarbela-sized reservoir every 10 years is necessary to meet the increasing demands of agriculture. It is also recommended to increase the storage capacity to 22 billion m<sup>3</sup> by 2025 to meet the projected requirement of 165 billion m3. If no new reservoirs are developed, the water availability will be reduced by 12% by the next decade due to sedimentation. Another reason for the development of new reservoirs is the increasing industrialization and urbanization, which demands more energy to fulfill their needs.

### *3.2. Extreme Events*

Extreme high and low temperatures, as well as the heaviest rainfalls, are all features of Pakistan's weather. In Turbat, Balochistan on 28 May 2017, a record-breaking 53.7 ◦C was measured, making it the hottest day in Pakistan's history [11]. On 26 May 2010, at Moenjo Daro, Sindh, Pakistan, a temperature of 53.5 ◦C was recorded, making it the second-hottest day in the country's history [12]. This was the fifth-highest temperature ever reported on Earth. On 23 July 2001, Islamabad received 620 mm of rain, the largest amount ever recorded rainfall in just 10 h.
