Sindh Climate

Forests are essential for human well-being and provide a wide range of ecosystem services to society, including ‘water retention’, defined as the water absorbed or used by forests.

Potential of Sindh’s Forest shows that water retention has an important role to play in buffering the effects of heavy rainfall and droughts. A better understanding of this role can help develop measures to tackle the effects of climate change and extreme weather events in the province.

The volume of water retained by forests can depend on characteristics such as forest cover area, the length of vegetation growing season, tree composition and tree density, as well as the age and the number of layers of vegetation cover. Water retention by forests affects the amount and timing of the water delivered to streams and groundwater by increasing and maintaining infiltration and storage capacity of the soil. Forests can soak up excess rainwater, preventing run-offs and damage from flooding. By releasing water in the dry season, forests can also help provide clean water and mitigate the effects of droughts.

The survey report shows that water retention potential tends to increase along with the extent of forest cover in a water basin. Compared to basins with a forest cover of 10%, total water retention is 25% and 50% higher in water basins where the forest cover is more than 30% and 70%, respectively.

The report suggests that despite its important role, water retention by forests cannot be promoted as a one-size-fits-all solution. Instead, water retention should be considered on a case-by-case basis according to local and regional ecological and hydrological conditions, as proposed in the Sindh Forests in different parts of the province.

According to data available on official website of Sindh Forest Department (SFD) https://sindhforests.gov.pk/page-aboutus

Sindh province, having a population of about 55.24 million, occupies land area of 14.091 million ha. (34.81 million acres). Out of above, an area of 1.125 million ha. (2.782 million acres) is under the control of Sindh Forest Department, which is 8% of the total area of the province. However, out of aforementioned total area, riverine forests and irrigated plantations which are categorized as productive forests cover only 2.29% area, clearly indicating that the province is deficient in forestry resources. The remaining area under the control of Sindh Forest Department (SFD) consists of mangrove forests and rangelands, which are classified as protective forests. The details of both productive and protective categories of forests are given as follows:

RIVERINE FORESTS:

Sindh Forest Department controls an area of 241,198 hectares in the Riverine tract of the province which are categorized as “Riverine Forests”; locally known as Kacho forests. These forests are located along both the banks of River Indus in Thatta, Hyderabad, Dadu, Larkana, Naushero Feroze, Nawabshah, Khairpur, Sukkur, Shikarpur, Ghotki and Jacobabad Districts and have been declared as “Reserved Forests” under Forests Act, 1927.

IRRIGATED PLANTATIONS:

Irrigated forest plantations of Sindh Forest Department cover an area of 82,195 ha. and have been declared as reserved forests.

RANGELANDS

Rangelands are ecosystems that play critical ecological roles which include: habitat for wildlife, source of biodiversity and pollution buffer. Furthermore, rangelands in Pakistan are a major source of forage for livestock, particularly sheep and goats. According to the report of Agricultural Statistics of Pakistan (1989-90), the population of sheep and goats has increased substantially over the last 30 years. The population of sheep has risen from 24.744 million in 2003-04 to 28.086 million in 2010-11, showing an average annual growth rate of  2% (approximately). Whereas the population of goats increased from 54.679 million in 2003-04 to 61.480 million in 2010-11 which an average annual growth rate of 1.25%.

MANGROVES

Mangrove forests of Indus delta, covering an area of about 600,000 hectares, constitute an important ecosystem in the coastal deltaic region formed by the River Indus. Indus delta mangroves are perhaps unique in being the largest arid climate mangroves in the world. They are almost entirely dependent upon freshwater discharges from the River Indus and a small quantity of freshwater from domestic and industrial effluents of Karachi.

Keeping in view the available data, it could be suggested that Sindh’s forest / trees help rain seep into soil because living and decaying roots make soil porous by creating a network of well-connected, minuscule channels in the soil. Rainwater seeps into soil with such channels several hundred times faster than it seeps through soil without channels.

Additionally, when plant debris falls on the soil and starts to organically degrade, it helps soil maintain integrity and form small aggregated clumps. These clumps also ensure that soil is porous.

When trees are taken off, floods often increase because most of the rainwater enters streams and rivers in a very short timeframe. Such high intensity flow is often not usable by human beings and usually flows into the ocean, while also causing soil erosion which leads to loss in soil nutrients. This is why large areas of formerly productive land, where annual rainfall is relatively high, have become desertified once tree cover is removed.

Reference:  A 2005 report by the Food and Agricultural Organization of the United Nations (FAO) available on record.