Glacier and river dynamics shaped irrigation systems and land use practices in Pakistan since the late 1700’s, according to a new paper by Sitara Parveen and his colleagues. These systems and practices can still be observed hundreds of years later, but they face severe challenges from glacier retreat.
Upper Hunza is located in the western Karakoram, Pakistan. The Hunza River flows north to south, and is joined by the Shimshal River from the northeast, and by the Batura, Passu, Ghulkin and Gulmit glaciers from the west. The melt runoff from the four glaciers supports approximately 20,000 people in Upper Hunza, and nurtures crops and orchards cultivated by villagers.
Steady and stable agricultural production requires constant and sufficient melt-water supply from glaciers and snowfields. The interactions between hydrological conditions and human communities in Upper Hunza are characterized by various aspects, including the arid environment of human settlements at lower altitudes, the dynamics of snow and ice cover at higher altitudes, the flexible water use practices, and diverse socio-economic conditions.
Upper Hunza is well known for its sophisticated irrigation systems. The earliest recorded irrigation channels in the valley date back to at least 1780 and diverted water from the Batura Glacier. To study the impacts of environmental and socio-economic dynamics on irrigation systems, Parveen and his colleagues examined the irrigation systems in three villages—Passu, Borith, Ghulkin—which are fed by different water sources.
In Passu Village, the largest settlement is located on three fluvial terraces at an elevation of about 2500m above sea level. Over the past 400 years, natural disasters have driven villagers to higher ground. They have also made several attempts to recover and rehabilitate barren land for crop cultivation. In 1983, a project to expand irrigable land was implemented by sourcing water from the Batura Glacier, however, the operation of this project was disturbed by the ups and downs in the volume of melt-water. Despite that, each household received one field on each terrace and 53% of the project area is transformed to irrigated fields.
In Borith, the main water sources are the Passu and Ghulkin glaciers. The community has made efforts to secure access to water due to frequent water crisis caused by glacier retreat since the 1950s. The northern part of Borith used to be served by Lake Ghyper Zhui, which began to shrink in the 1940s as the Passu Glacier started to become thinner with melting. Several attempts were then made to conserve the melt water flow into the lake, with the expansion of natural irrigation channels through daily excavation works. However, all the efforts turned futile as soon as the glacial runoff proved to be insufficient and the land returned to a barren state.
Lower Borith sources all of its water from Ghulkin Glacier. Since 1960, many channels have been constructed, adjusted and constantly maintained to divert water in response to the continuous thinning of the glacier, which is highly labor-intensive. As the majority of households migrated from the community due to ongoing declining water resources, an increasing number of fields have gone idle. New pipelines were installed in 2013, but the problem of shifting water sources still remains.
Ghulkin is located between two glaciers—Ghulkin and Gulmit. The village is also facing water shortage due to increasing glacier down-wasting. The problem is even more aggravated by the dispute over water use rights between the original inhabitants and the relatively new immigrants. A water management committee was thus established, but does not function well because the original settlers upstream often ignore the arrangement, leaving the downstream people helpless. Some villages constructed new irrigation channels and cultivated different, drought-tolerant crops.
The dynamics of glaciers and rivers in Upper Hunza have a considerable impact on local adaptation practices and land use patterns. The fluctuation in water supply is one of the major constraints in local communities. Glacier related natural disasters further contribute to the vulnerability of local irrigation systems and livelihoods as well. To make it even worse, the villages lack a sufficient work force to maintain the irrigation systems and manage the problems brought by glacier dynamics, such as equitable water distribution.
Communities of Upper Hunza have experienced substantial external interventions over the past century, and the impacts of glaciers and rivers will extend into the future. The study conducted by Parveen et al. sheds light on irrigation construction and improvement, especially for high mountain areas. Other high mountain communities can also learn from the lessons of Upper Hunza when coping with the effects of climate change.