Tap­ping the sur­face runoff

Down to Earth - - LAKES - DOWN TO EARTH



RULERS OF Chhattisgarh since the 10th cen­tury un­der­stood the to­pog­ra­phy and soil char­ac­ter­is­tics of the area and took ad­van­tage of that to make wa­ter bod­ies across the city.

The top soil in most of the state has shale and sand­stone. It is im­per­me­able and helps in wa­ter re­ten­tion. This also means ground­wa­ter is scarce. So the rulers, early on, started de­vis­ing ways to tap sur­face runoff keep­ing in mind the scarce ground­wa­ter.

The first lakes were built on land that re­mained wa­ter­logged for more than three months. The rulers lakes, spread over 69.239 hectares, are pol­luted and heav­ily silted.

Flood of dis­eases


Wa­ter sam­ples an­a­lysed by Shende and his team show ab­nor­mal lev­els of E coli con­tam­i­na­tion along with pres­ence of ni­trates in higher con­cen­tra­tion in drink­ing wa­ter. In fact, in 2013, 627 cases of wa­ter­borne dis­eases in the city were a re­sult of poor san­i­ta­tion and un­hy­gienic con­di­tions.

Shende’s find­ings are cor­rob­o­rated by Bod­hankar who con­nects the wa­ter­borne dis­eases to block­ing of drains and sub­se­quent flood­ing dur­ing mon­soons. “Peo­ple blame the wa­ter bod­ies for flood­ing but in­dis­crim-




also wanted to connect the lakes so that ev­ery drop of rain­wa­ter is con­served. Be­cause of th­ese con­nec­tions, some lakes were con­sid­ered mar­ried to each, some were called sib­lings and oth­ers were un­cle-nephew lakes.

Over a pe­riod of 500 years or so, plan­ners of the city made wa­ter bod­ies inate dump­ing of garbage is what blocks their neigh­bour­hood drains. Wher­ever there are gaps in the wa­ter dis­tri­bu­tion net­work, the con­tam­i­nated wa­ter gets mixed with drink­ing wa­ter,caus­ing dis­eases,”Bod­hankar says. Abid Ali Khan, who con­ducted a case study for Royal Haskon­ing dhv, a pre­mier en­gi­neer­ing and con­sul­tancy or­gan­i­sa­tion of the Nether­lands, in as­so­ci­a­tion with giz, on im­prove­ment of storm wa­ter man­age­ment in Raipur, warns that low-ly­ing ar­eas of the city will get flooded if rain­fall ex­ceeds 100 mm in a day.

As most ex­perts, in­clud­ing Bod­hankar, Shende and Khan,say the drainage sys­tem is di­rectly linked to wa­ter bod­ies, the mu­nici-


It is sit­u­ated at the high­est altitude of the city. Tra­di­tion­ally, rain­wa­ter would first fill the lake and the ex­cess wa­ter would flow to the other lower lakes. But peo­ple have en­croached the catch­ment ar­eas of most lakes Most of the chan­nels are blocked be­cause of the dump­ing of un­treated waste. This, along with en­croach­ment on lakes, leads to ur­ban floods in el­e­vated ar­eas in the di­rec­tion of de­scend­ing el­e­va­tion. Once rain­wa­ter or sur­face wa­ter would fill the struc­ture at the high­est el­e­va­tion, it would over­flow or spill into the suc­ces­sive struc­ture, lead­ing to con­ser­va­tion of ev­ery drop flow­ing to­wards the stream or river. pal cor­po­ra­tion has to in­ter­vene.While rmc needs to recog­nise the im­por­tance of th­ese wa­ter bod­ies,Khan says,drainage has to im­prove. “The sewage sys­tem needs im­prove­ment and the catch­ment area of all lakes should be de­mar­cated so that waste wa­ter can be lo­cally treated and di­verted to the lakes. Open dump­ing of waste has to stop,”he adds.

But as with other mu­nic­i­pal­i­ties, rmc too faces acute staff short­age and the tenures of se­nior of­fi­cials, who can per­haps over­see projects to im­prove san­i­ta­tion, are too short for long-term work. In such a sce­nario, the Chhattisgarh gov­ern­ment and its elected mem­bers have to do more than just say that ponds and lakes are cul­tural her­itage.

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