3. STUDY on WATER RESOURCES POTENTIAL 3.1 Surface Water

The Study on Water Supply Systems in Mandalay City and in the Central Dry Zone Part III Study for the Central Dry Zone

3. STUDY ON WATER RESOURCES POTENTIAL

3.1 Surface Water Resources

3.1.1 Introduction

As stated in Paragraph 1.1.2 Climate, the Central Dry Zone has a very hot and dry climate with an average annual rainfall of 699 mm over 6 townships of Mandalay Division and 687 mm over 5 townships of Magway Division. Study on township-wise annual rainfalls reveals that the annual rainfall varies from township to township in the Central Dry Zone with the highest at Magway township (842 mm) and the lowest at Yezagyo township (432 mm). Due to such low annual rainfall, the Central Dry Zone has very scarce surface water resources. It has no perennial river of its own except the Ayeyarwaddy River which flows through the center of the Central Dry Zone passing by the cities like Mandalay, Myingyan, Yezagyo, Pakokku, Nyaung U, Chauk, Yenangyaung, Sale and Magway. Since the Ayeyarwaddy water has no particular problem as a source water for domestic use and also it is large in quantity, these cities have comparably a favorable water environment. But many towns and villages in the Central Dry Zone, which are far away from the Ayeyarwaddy River, are lacking a good water environment. The people in those areas have to rely on groundwater or small storage ponds’ rainwater for drinking. In most areas of the Central Dry Zone, groundwater is available by digging shallow or deep tube wells, but potable groundwater is hardly found. No matter potable or not potable, the people in the Central Dry Zone are happy when water is made available.

3.1.2 Seasonal Rivers

Speaking about surface water resources, there are numerous seasonal rivers in the Central Dry Zone. All these rivers mostly originate from Mount Popa, the only mountain in the Central Dry Zone with a peak of 1518 m above sea level. These rivers have water flowing in the river channels during the time of rainfall in their catchment basins. When the rain stops continuously for two to three days, no water can be seen flowing in these rivers. The water quality of a seasonal river varies from river to river depending upon the type of soil strata upon which the river flows. When the river flows upon the shale, sandstone and salt-rich rock area, the water shall be colorless and salty and if the soil strata is made up of Irrawaddy formation, then the water quality shall be good and potable, but the river water shall have sand and silt particles in suspension. The water shall be brown and reddish during flood, but become colorless a few days after flood.

There are three big seasonal rivers in the Central Dry Zone. They are the Sindewa Creek, the Pin

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Creek and the Yin Creek (refer to Fig.3.1.1.). These big seasonal rivers (in the true sense of the word, “creek” is locally used instead of “river” for seasonal rivers) are quite important for the livelihood of the people living around these rivers. Here the term “river” shall be used instead of “creek”. For location of these Sindewa, Pin and Yin rivers, refer to Fig.3.1.1.

(a) The Sindewa River

The Sindewa seasonal river originates from Mount Popa and flows down to the flat land on the northern side of Popa. It empties into the Ayeyarwaddy River at a place about 10 km downstream of Myingyan. The river is 800 - 1500 m wide around Welaung. The river has a total length of 85 km from the origin to the confluence with the Ayeyarwaddy River. The river flows by the side of Welaung, Taungtha and several small villages in Myingyan District. Sindewa is a lifeline for the people living by the side of the river, because it is a source of domestic water in that part of the country. In those areas like Welaung, Taungtha and near by villages, groundwater is available by digging 20 m to 100 m almost any where, but almost all these wells’ water is salty and not potable.

Sindewa has many tributaries which are contributing to its discharge to such an extent that Sindewa has water flowing almost all the time during Monsoon season. Since Sindewa flows on the land made up of Irrawaddy formation, the river is carrying a lot of sand, but the water quality is quite good. The people get potable water from Sindewa by digging hand-dug wells of 1 to 2 meters depth at its riverbed. Recently an embankment dam called Themetku Dam has been constructed across the Sindewa river at a place called Thametku, near Welaung, by the Ministry of Agriculture and Irrigation. This dam is designed and constructed for the purpose of irrigation only. The purpose of supplying drinking water to villages nearby has not been incorporated in the dam design. Another dam called Welaung Dam has been constructed near Welaung on the tributary of Sindewa, but it is learnt that village domestic water purpose (drinking water component) has not been included in the dam design.

(b) The Pin River

The Pin seasonal river originates from Mount Popa and flows down to the flat land on the southern side of Mt. Popa. It empties into the Ayeyarwaddy River at a place just upstream of Yenangyaung. The river is 800 - 1000 m wide around Yenangyaung. The river has a total length of 75 km from the origin to the confluence with Ayeyarwaddy. The river flows by the side of Kyaukpadaung and several small villages in Kyaukpadaung Township. Pin is a lifeline for the people living by the side of the river, because it is a source of domestic water in that part of the country. In those areas, groundwater is

3-55 The Study on Water Supply Systems in Mandalay City and in the Central Dry Zone Part III Study for the Central Dry Zone available by digging 20 m to 100 m almost any where, but almost all these wells’ water is salty and not potable.

Pin has many tributaries which are contributing to its discharge to such an extent that Pin has water flowing almost all the time during Monsoon season. Since Pin flows on the land made up of Irrawaddy formation, the river is carrying a lot of sand, but the water quality is quite good. The people get domestic water from Pin by digging hand-dug wells of 1 to 2 meters depth at the river bed. Around 1972, an embankment dam called Kyetmauktaung Dam has been constructed across the Pin river at a place near Kyaukpadaung by the Ministry of Agriculture and Irrigation. This dam is designed and constructed for the purpose of irrigation only. The purpose of supplying domestic water to nearby villages has not been incorporated in the dam design. Another dam called Pin Chaung Dam has been constructed on the Pin river, but it is learnt that the purpose of supplying domestic water to towns and villages has not been included in the dam design.

The Yin seasonal river originates from the high land around Pyawbwe and flows down to the flat land on the southern side of Mt. Popa. It empties into the Ayeyarwaddy River at a place about 10 km downstream of Magway. The river is 1000 - 1200 m wide around Natmauk. The river has a total length of 95 km from the origin to the confluence with Ayeyarwaddy. The river flows by the side of Nyaungyan, Kyekan, Ywamon, Natmauk, Myothit and several small villages in Magway Township. Yin is a lifeline for the people living by the side of the river, because it is a source of domestic water in that region. In those near by villages, groundwater is available by digging 20 m to 10 m almost any where, but almost all these wells’ water is salty and not potable.

The Yin River is very similar to the Pin River in the aspect of sediment load. A great volume of sand and gravel is brought into the river as a result of river bank and land erosion. Hence it has a lot of sediment load. Natmauk weir near Natmauk and Saddan dam near Myothit have been designed and constructed across the Yin River by the Ministry of Agriculture and Irrigation. These water utilization structures are designed and constructed for the purpose of irrigation only. The purpose of supplying domestic water to towns and villages nearby has not been incorporated in the dam design.

3.1.3 Utilization of Surface Water

From the foregoing paragraph, it is clarified that the three big seasonal rivers have numerous tributaries.

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And in terms of discharge, Yin has the biggest followed by Sindewa and Yin in the decreasing order. When the flow quantity of these rivers and tributaries are combined, the volume of surface water shall be considerable. Assuming that the catchment width of each river is 10 km, the total catchment of the three rivers will be (85+75+95)x10=2550 km2x106 m2, the annual total runoff is: Q = 2550 x 106 x (699+687)/2 x10-3 x 0.3 (coefficient of runoff) = 530 million m3 (a rough estimate)

It can be said that the Central Dry Zone has a sufficient quantity of surface water. It seems however true that the surface water is not fully utilized. It is mostly utilized for the sole purpose of irrigation in the Central Dry Zone. In such dry zone area where water is precious, multi-purpose usage of water together with reuse of discharged water from irrigated tracts should be taken into consideration in a project study. Multi-purpose usage includes town and village water supply, industrial use, cleansing roads and facilities for health and hygiene of the people, irrigation, hydro-power, etc.

In the Central Dry Zone, surface water utilization for domestic purpose is rather few. Rainwater storage tanks are built for drinking purpose by the peoples’ own effort. But these are of small scale since they are built by peoples’ effort. A rainwater storage tank called Bonzin dam (high quality water) at Taungtha is built by the peoples’ effort and it is large enough in storage volume, but due to lack of proper piping system, less than 50% of the high quality water reaches Taungtha city’s residents. This is a good example of surface water utilization for drinking by rain water storage tank. Similar projects should be envisaged in other towns in the Central Dry Zone. Sindewa has a great amount of surface water stored in its alluvial (sand and gravel) bed. Sindewa water utilization plan has been formulated by the Water Resources Utilization Department around 1994. The plan contemplates that the water in the Sindewa River’s alluvial bed shall be pumped up to a higher elevation on Mount Taungtha and from there piped domestic water shall be supplied by gravity to Taungtha and Myingyan cities including near by villages. This is quite a dramatic scheme. Request for assistance has been made to Australian Development Assistance Bureau (ADAB). But it was of no avail. The project was not materialized until the present time.

3.1.4 Recommendations on Surface Water

Since surface water resources are scarce, utmost utilization of surface water is essential in the Central Dry Zone. The following are recommended for the utmost utilization of surface water resources in the Central Dry Zone.

(1) River laws and river development code of practice should be enacted.

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In this river law, Myanmar’s rivers shall be classified into three grades, Grade I, Grade II and Grade III. The river law should be enacted such that Grade I rivers shall be under the jurisdiction of the central government, Grade II rivers under the control of division or state and Grade III under the control of district or township. In that code of practice, the important clause shall be such that the objectives of a water resource development project shall be thoroughly defined and it shall be as much possible as “multi-purpose”, which means that the water supply objective shall be included in a water resource development scheme as the legitimate right of the people living near the water resource.

(2) A water utilization coordinating committee shall be formed.

The committee shall be made up of one director from the Department of Development Affairs, one director from the Department of Irrigation, one director from Myanma Electric Power Enterprise, if and when necessary one director from the Inland Waterways Department. The committee shall evaluate, examine and monitor the water resource development and oversee whether the project shall satisfy as many users as possible before a project is implemented.

(3) Dam Design Guide Lines

Dam design guide lines on water quality, environmental considerations, indirect benefits gained from environmental upgrading, etc. should be adopted in “dam design criteria”.

3.1.5 Conclusion

Studies on the rain water storage dams in the Central Dry Zone should be conducted for the purpose of supplying domestic water to villages. These dams shall serve the people not only with good water, but also with a very desirable natural and ecological environment.

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Fig.3.1.1 LOCATION OF SEASONAL RIVERS IN CENTRAL DRY ZONE

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