HYDRO-ECOLOGY CONFERENCE IN INDONESIA 2014

Global water environment has deteriorated and there has been significant loss of biodiversities worldwide, which severely impacts global ecosystems. Such trends provide ample evidence that conventional approaches to water resources management (based on the application of engineering techniques, sectoral interventions, and the elimination of such direct threats as point source pollution) are no longer sufficient to stem the tide of the water crisis. Ecohydrology aims to find solutions that, rather than focusing exclusively on technical issues, better respond to sustainable water resource policies and promote social development.

Ecohydrology is a new integrative science that involves finding solutions to issues surrounding water, people, and the environment. One of the fundamental concepts involved in ecohydrology is that the timing and availability of freshwater is intimately linked to ecosystem processes, and the goods and services provided by freshwaters to societies. This means that emphasis is placed on the hydrological cycle and its effects on ecological processes and human well-being.

To bring the concerned people together and to discussed the issues on ecohydrology a Conference had been organized in conjunction with the 22nd Meeting of the International Hydrological Programme (IHP) Regional Steering Committee (RSC) for Southeast Asia and the Pacific under the topic “Ecohydrology Approaches Facing the Global Water Environment Challenges”.The objectives of the proposed International Conference on Ecohydrology (ICE) held from 10-12 November 2014 was aimed to synthesize information and knowledge gaps for addressing issues related to critical water environment systems; how the ecohydrology and ecotechnology could provide low cost environmentally sound technology for sustainable water management, especially in the Asia Pacific region. The past experiences and on-going projects related to terrestrial ecosystems processes, water issues in landscapes, rivers, floodplains, wetlands, reservoirs, coastal and urban areas will be discussed in the Conference.

The conference venue was the Royal Ambarukmo Palace Hotel at Yogyakarta, Indonesia.

One of the fundamental concepts involved in ecohydrology is that the timing and availability of freshwater is intimately linked to ecosystem processes, and the goods and services provided by freshwaters to societies. This means that emphasis is placed on the hydrological cycle and its effects on ecological processes and human well-being.

Global water environment has deteriorated and there has been significant loss of biodiversities worldwide, which severely impacts global ecosystems. Such trends provide ample evidence that conventional approaches to water resources management (based on the application of engineering techniques, sectoral interventions, and the elimination of such direct threats as point source pollution) are no longer sufficient to stem the tide of the water crisis. Ecohydrology aims to find solutions that, rather than focusing exclusively on technical issues, better respond to sustainable water resource policies and promote social development. Ecohydrology is a new integrative science that involves finding solutions to issues surrounding water, people, and the environment.

The subtopics of the conference were:

1.        Development of Ecohydrological Concepts and Implementation Issues

2.        Ecotechnology for Water, Food and Energy Security

3.        Sustainability Issues in Water Environment

4.        Ecohydrology in Lakes and Reservoirs

5.        Ecohydrology in Wetlands

6.        Ecohydrology in Karst and Terrestrial Ecosystems

7.        Hydroinformatics and Modelling

8.        Human and Water Environment

9.        Local Tradition, Knowledge , Wisdoms and Cultural Values

10.    Water Environment Related Disasters

11.    Governance and Management Challenges

12.    Biodiversity and Water Environment

13.    Public Participation

The conference was sectioned in four parallel sessions where about 70 papers were presented. More than 200 delegates from different countries of Asia and Europe attended the conference.

The programme for third day was a field trip to the spring zone of Merapi volcano, the villages of Kali Khod and to the water castle of Taman Sari. One of the main tourist spots of Yogyakarta is the 800 AD Prambanan temple. This was also included in the field trip.

The main take away from the conference is that Ecohydrology is developing as a separate paradigm in the context of human- nature-water relationship. The understanding of the changes in the backdrop of climate change and anthropogenic activities the new science is gaining importance. Some of the research papers from Indonesia, Thailand and China had been very thought provocating and contained serious efforts in depicting the science in local contexts.

The conference was organized by UNESCO, Indonesia and the Asia Pacific Centre for Ecohydrology, Jakarta, Indonesia in collaboration with some other related organizations.

RAINWATER HARVESTING IN KOLKATA MUNICIPAL CORPORATION AREA

INTRODUCTION: Kolkata is now a great megalopolis with about ten million populations. This city is not only growing in size but also growing in population day by day. This growth of population has cast a great impact on the land on one hand and on the other hand the demand for drinking water has grown by many folds.

The history of Kolkata water supply starts from the initiation of the British settlement in 1717 and runs up to 1870 when Calcutta Municipality was establish. During the various phases of formation of Calcutta municipality, topmost priority was given to water supply problems. The water supply of the newly constituted municipality commenced in the year 1870 with a 6 mgd plant at Palta. To cope with the increasing demand of portable water, the capacity of the water treatment plant was augmented in stages. In addition, there is 60 mgd of unfiltered water supply and ground water supply of 22 mgd by 260 deep tube wells.

At the increase in demand of water more and more hand tube wells were installed during the last two decades. Apart from private initiative the corporation has also installed a number of deep tube wells fitted with hand pumps.

The actual number of private deep tube wells is yet to be known. But withdrawal of ground water has increased to a great extent during the last two decades. This unaccounted has developed two major groundwater problems: -

a) Depletion of water level to the tune of 10-12mbgl at places.
b) Deterioration of water quality.

Geologically and geomorphologically Kolkata belongs to the lower deltaic plain of the Ganga-Padma river system.. The surface material is clay and clay loam. This clay extends up to a depth of 10 to 25 m bgl in most of the area. Below this clay bed a fine sand bed is found which extends up to a depth of 30-to 35-metre bgl. Below this level another clay, dark brown to grayish brown in colour occur up to a depth of 60 to 100-metre bgl. From this depth another sand zone occur which comprises of fine, medium and coarse sand and extends up to a depth of 120 to 180 metre bgl. Below this sand zone gravel bed occurs. Tertiary black and sticky clay occurs at the bottom of the sand and gravel zone.

Due to unique geological setting rainfall in Kolkata does not percolate downwards to recharge the groundwater regime. Rainwater is totally wasted and poses a serious problem like water logging and sewage overload.

The demand of water for domestic purpose in Kolkata is increasing day by day. The municipal water supply to some extent and private domestic water supply in some areas also depend on ground water. Since Kolkata is not within the groundwater recharge zone and the withdrawal of groundwater is very high in comparison with the groundwater recharge from remote area groundwater level has already depleted to a great extent. Recent studies have revealed that groundwater level of Kolkata has already gone down to 10 to 13 metre below sea level. .

To combat all the problems related to the water supply and demand, and also for the problems developed due to over withdrawal of groundwater scientists are advising to utilize rainwater in urban areas.

BENEFIT: Rainfall in Kolkata occurs during the monsoon. Maximum rainfall occurs from June to October. The average annual rainy days are 60. Average daily rainfall is about 30 mm considering only the rainy days. The monthly average rainfall is given below.

The volume of total annual rainfall in Kolkata over a 184 sq km area is 1.402X 184= 258 million cubic metres. This amount of water is required for 10 million people for 151 days. In the same way rainwater available on a 100 sq metre roof is 1.402 X 100 cubic metre annually= 140200 litres. This is enough for a family of five for 140 days.

PRACTICAL VIEW

It will never be possible to harness all available rainwater through any type of harvesting system. Moreover the water requirement of Kolkata is much higher than the amount of rainfall falling directly overhead. So Kolkata will remain dependant on the transported water from upstream regions. But rainwater harvesting in Kolkata has three visible benefits.

1) If a large amount of rainwater is used for groundwater recharge it will supplement the natural recharge to some extent.
2) If about 10% of rainwater is harvested properly through some well managed system in specific locations it will significantly reduce water logging during storm seasons.
3) If rainwater is harvested by individuals or by community housing societies the consumption of piped water will be reduced to a great extent. The Loreto Day School in Sealdah is utilizing rainwater for its toilets and significantly reduced municipal water consumption.