Land Use Planning and Management in Tank Cascade Environment of Sri Lanka

Land Use Planning and Management in Tank Cascade Environment of Sri Lanka

Muditha Prasannajith Perera (University of Peradeniya, Sri Lanka) and K. W. G. Rekha Nianthi (University of Peradeniya, Sri Lanka)
Copyright: © 2021 |Pages: 20
DOI: 10.4018/978-1-7998-4372-6.ch016
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The Tank Cascade System is one of the unique and socially accepted land-use practices in the dry zone of Sri Lanka which has evolved since 600 B.C. The small tank builders of the historical period had a profound and unified understanding of the natural resources, regional landscape, landforms, and hydrology. Tanks and irrigation canal systems, environmental zoning, forest reservations, agro-well-based land utilization, land-sharing system (Bethma), traditional soil conservation measures have been still maintaining well in some rural areas in the dry zone. Newly developed agro-well-based agro-forestry systems and some participatory techniques are also counted as few of sustainable land-use practices. This study has provided many valuable lessons of land use planning and management from the ancient hydraulic civilization and proving that the ancient system is still appropriate for the dry zone agricultural community rather than inadequately coordinated modern efforts of land use practices.
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The history of irrigation civilization in Sri Lanka goes back to over 2000 years (Brohier, 1934). Irrigation development in the country linked with paddy cultivation which is the staple food for Sri Lankans. In addition to that, the home gardens and chena1 cultivations are alsopracticing using rain water. Currently the overall land use pattern has been changed with the new agricultural interventions such as agro-well practices. The historical hydraulic civilization of the dry zone of Sri Lanka which prevailed in the North Central part (Rajarata) of the country, is a unique place to study the indigenous techniques of land use practices. It is the Northern part of the Central mountainous and the central part of the inland plain of the country. The mountainous areas covered by the forest and act as a sponge to capture rain water and release water in the dry season to the downstream. November to January is the main rainy season, and over 70% of the total rainfall receives during this period and others months remain dry. It was the major challenge of the dry zone peasant farmers to cultivate throughout the year. The rainfall pattern and the values of landscape initiate the necessity of a water-stored system and better land use practices. In the third and fifth century, advanced hydraulic structures including tanks and irrigation canal systems have been designed and constructed which would have required a sound knowledge of some of the key hydrological relationships pertaining to rainfall, runoff, storage volume and land management processes (Panabokke,2002).

The study area of this current research belongs to the dry climatic zone of the island. The most important climatological feature of the region is that receiving more rainfall from the Northeast Monsoon season. Average annual rainfall for the area is between 1250 mm - 1400 mm. The distribution pattern of rainfall shows the bi-model pattern with a maximum of rain from November to February and a minimum rainfall received from May to September. The monthly mean temperature of the area is 28°C which falls to the lowest value of 25°C in January and the highest value of 32°C in April. The wind directions are from Northeast direction between December to February and from Southwest direction between May to September. The central dry zone area mainly falls in to the ‘DL 1 Agro Ecological Region’ of Sri Lanka (National Atlas of Sri Lanka, 1998). The major vegetation types include as tropical moist deciduous forests and scrub lands.

The natural drainage patterns in relation to the location of individual tanks reveal an effective pattern and it is now referred to as the “small tank cascade system” (Madduma Bandara, 1985). There are some other local terms such as “Ellangawa” (Thennakoon,2005) and “Wew Mandulla”(Perera, 2010) referring that the tanks are connected series. However, these cascade systems2 located in meso catchments make up a micro or sub-watershed and several sub watersheds make up a main watershed in the dry zone of Sri Lanka (Panabokke,2002). Thus, the entire part of the Rajarata consists of nine watersheds including 50 sub watersheds and all these sub watershed areas have been converted into “Tank Cascade Systems”. It refers connected series of tanks with micro catchments and command areas, organized within a small valley. The tank system is integrated in to all land use systems in the vicinity of tanks. Accordingly, major land uses are tanks, streams, paddy lands, home gardens, road system, chena land, forests, riverine forests, tank reservations such as gasgommana (a dense forest patch in the immediate catchment), kattakaduwa (interceptor belt between tank and the paddy field), agro-wells and agro-well based lands (Figure 1).

Figure 1.

Land use in selected tank cascades in Malwathu Oya Basin

Source: Modified from Geo eye 1 satellite images, 2012.

Key Terms in this Chapter

Empherical Knowledge: Indigenous knowledge with practical experience.

Agroforestry Systems: Agricultural activities with woody trees.

Tank Reservations: Different forest reserves in the vicinity of tanks.

Tank Cascades: Connected series of tanks with micro catchments and command areas, organized within a small valley.

Agro-Wells: Large diameter wells for agricultural activities.

Bethma System: Sharing of one part of the paddy land among all farmers in the dry season, due to scarcity of water.

Woody trees: Tree species with timber value.

Chena Lands: Dry zone mixed farming system, without a home garden.

Hydraulic Civilization: Civilized community based on irrigation activities.

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