Need for water harvesting at Awang Sekmai, Manipur and Artificial Recharge Techniques
- Part 1 -

L Sherjit Singh *

Sekmai Turel Kansi : International Day of Action against Dams, for Rivers, Water at Sekmai River on 14 March 2013

Abstract

Water is the precious gift of nature. We cannot live without water.70% of our body weight is water. Our blood contains 95% water. Due to over population urbanization and industrialization, the demand of water is rapidly increasing .Most of the countries of the world face water crisis. Our India is one of them. The study area is located about 20 km from state capital. Sekmai town is located in the Imphal West district of Manipur. The coordinates are 24°58'17"N and 93°53'4"E. The incredibly beautiful river side town is located amidst the Nongpok Ningthou Hill, Koubru Hill, Khurkhul and Kounou Hills. The town is located along the Sekmai River.

Awang Sekmai which is a part of Imphal valley enjoys a very pleasant climate which is neither hot nor cold and thus makes the area a suitable place for healthy living. The average maximum temperature prevails for whole Imphal valley including Sekmai ranges between 140 to 320C during summer and up to 250C during winter. The area is covered by varieties of flora ranging from herbs to shrubs to tall trees

The pre-monsoon rain begins towards the end of April-May and continues sometimes up to September with maximum amount of rainfall in the month of June and July. The annual rainfall values range between 824.90 mm to 1467.5 mm approximately. People of Awang Sekmai use wells and tube wells for domestic purposes. But it is found that the level of water table is declining. We need to conserve water & aquifer because once aquifer loses its property, it cannot regain. Artificial recharging techniques like Stream modification, Check dam, Recharge wells, Percolation ponds and Recharge pits and shafts may be installed to solve the problems.

Introduction

Manipur is a small state located in a hilly terrain with a small portion of valley. It has complex geology, geography, geomorphology, and lithology. Once upon a time Manipur valley was full of lakes. Most of the Lakes become vanishing with the course of time. Some of them remain only for namesake. Many ground water recharging structures like ponds, tanks and swampy areas are greatly reduced due to urbanization and change in land use pattern .

Rivers are greatly polluted in many parts of the state .But demand of water is increasing day by day due to rapid increase in population. So Manipur is facing water problems. Awang Sekmai which is located in Imphal valley is one of them. Traditionally people use wells and tube wells for domestic purposes. Nowadays water table is rapidly declining in that area due to over exploitation. People are favored in deeper wells .Now it is necessary to construct recharging structures to conserve ground water for future.

About the Study Area

1.1 Location of the Study Area

Sekmai town is located in the Imphal West district of Manipur. The coordinates are 24°58'17"N and 93°53'4"E. It is 20 km from the state capital Imphal. The incredibly beautiful river side town is located amidst the Nongpok Ningthou Hill, Koubru Hill, Khurkhul and Kounou Hills. The town is located along the Sekmai River.

1.2 Geomorphology, Lithology and Drainage

From the geomorphic point of view Awang Sekmai is located in an alluvium fan deposit which is bordered by low hills. The ephemeral Sekmai River flows through the study area. Small scale quarrying of construction materials like sand, gravel and sometimes large boulders is done in the river terraces.

Lithologically, the area consists of soil (including clay and organic matter), sand, gravel, pebble, boulder deposits and old river terraces.

1.3 Climate and Vegetation

Awang Sekmai which is a part of Imphal valley enjoys a very pleasant climate which is neither hot nor cold and thus makes the area a suitable place for healthy living. The average maximum temperature prevails for whole Imphal valley including Sekmai ranges between 140C to 320C during summer and up to 250C during winter. The area is covered by varieties of flora ranging from herbs to shrubs to tall trees.

1.4 Rainfall / Precipitation

The pre-monsoon rain begins towards the end of April-May and continues sometimes up to September with maximum amount of rainfall in the month of June and July. The annual rainfall values range between 824.90 mm to 1467.5 mm approximately.

1.5 Source of water

Wells and tube wells are the important sources of water for domestic purposes. The source of water for irrigational purposes is Sekmai River.

2.1 Causes of water problem

a) Over exploitation or excessive pumping to meet increasing water demand
b) Over population and excessive consumption
c) Urbanization and increased of paved surface area
d) Lack of traditional water conservation structures like ponds and tanks
e) Non availability of other source of water for domestic uses
f) Most of rainwater is drained out without enough recharging aquifer
g) Lack of awareness
h) Insanitary disposal of waste to river and streams

2.2 Artificial recharge techniques

The artificial recharge techniques can be broadly classified as follows (modified from CGWB)-

I) Direct methods
A) Surface flooding techniques
a) Flooding
b) Ditches and Furrows
c) Recharge basins
d) Run off conservation structures

i) Bench Terracing

ii) Contours bunds and Contour terracing

iii) Gully pluges, Nalah bunds, Check dams

iv) Percolation ponds
e) Stream modification/Augementation
f) Irrigation methods

B) Sub surface techniques
a) Injection/ Recharge wells
b) Gravity head recharge wells c) Recharge pits and shafts

II) Indirect Methods
A) Induced recharge from surface water sources
B) Aquifer modification
i) Bore Blasting
Ii) Hydro fracturing
III) Combination of any above

To be continued...