362
N. Pradhan et al.
and filtration (Islam et al. 2016). There are various methods for recharging water like
infiltration process and well injection method useful for unconfined and confined
(deeper) aquifer, respectively. The various types of MAR include aquifer storage
and recovery (ASR), where water is injected into a well and then recovered from
same well. This method is useful for brackish aquifer, where water storage is more
important rather than its treatment. In northeast region of India, this type of technique
is used for rainwater harvesting (Philp 2007; Islam et al. 2015).
Infiltration gallery and infiltration ponds or basin are also used for aquifer recharge
where urban runoff and treated waste water diverted into a pond and soaked under
the unconfined aquifer. Such type of arrangement is made near the treatment site so
as to reduce the pumping cost. Similarly rain water harvesting is also a beneficial
technique as roof runoff is stored in ground via well or caisson and hence it avoids
evaporation loss. This helps to reduce surface runoff which in turn enhances the
groundwater recharge. RWH along with infiltration gallery can help to change the
urban climate and lessen the heat island effect.
The quality of recharge water can ameliorate or improve through aquifers via
natural processes: redox transformation (nitrification, denitrification etc.), sorption,
filtration, and degradation. The aquifer matrix conditions should be such that it should
be able to predict the natural attenuation rates for specific site condition. There are
several studies which are related to check the aquifer matrix based upon nutrient
content, total organic carbon (TOC), microbial pathogens, trace organic chemicals,
and antibiotic resistant genes. An infiltration gallery site in Western Australia shows
significant reduction in the concentration of phosphorous (P) and total organic carbon
(TOC) as 30% and 51%, respectively, in unsaturated zone (Bekele et al. 2011). It is
also stated that removal efficiencies are clearly defined for the particular infiltration
rate of recycled water and aquifer conditions. Carbonate configuration of aquifer
plays a major role to show the sorption mechanism of phosphate.
15.6 Challenges and Opportunities of Water Management
Some of the key issues which we are facing and which needs to be considered and
are evolving with time include:
Climate change: Previous studies and analysis show that there was not much fluctuations on hydrological management through climate change; but now, due to severe
drying and warm climate, there is lesser water availability. Initially observed data are
now not suitable to plan for variability in climate. It is mandatory to have information about how probability is affected by climate change so as to carry out risk-cost
analysis of alternative outlay in infrastructure required in the future.
Growth in urban demand: The population in urban areas is continuously growing
with the spread in urban areas thus placing pressure on water supply system to avail
the water for them. In recent decade, on globalscale, increase in percentage in water
N. Pradhan et al.
and filtration (Islam et al. 2016). There are various methods for recharging water like
infiltration process and well injection method useful for unconfined and confined
(deeper) aquifer, respectively. The various types of MAR include aquifer storage
and recovery (ASR), where water is injected into a well and then recovered from
same well. This method is useful for brackish aquifer, where water storage is more
important rather than its treatment. In northeast region of India, this type of technique
is used for rainwater harvesting (Philp 2007; Islam et al. 2015).
Infiltration gallery and infiltration ponds or basin are also used for aquifer recharge
where urban runoff and treated waste water diverted into a pond and soaked under
the unconfined aquifer. Such type of arrangement is made near the treatment site so
as to reduce the pumping cost. Similarly rain water harvesting is also a beneficial
technique as roof runoff is stored in ground via well or caisson and hence it avoids
evaporation loss. This helps to reduce surface runoff which in turn enhances the
groundwater recharge. RWH along with infiltration gallery can help to change the
urban climate and lessen the heat island effect.
The quality of recharge water can ameliorate or improve through aquifers via
natural processes: redox transformation (nitrification, denitrification etc.), sorption,
filtration, and degradation. The aquifer matrix conditions should be such that it should
be able to predict the natural attenuation rates for specific site condition. There are
several studies which are related to check the aquifer matrix based upon nutrient
content, total organic carbon (TOC), microbial pathogens, trace organic chemicals,
and antibiotic resistant genes. An infiltration gallery site in Western Australia shows
significant reduction in the concentration of phosphorous (P) and total organic carbon
(TOC) as 30% and 51%, respectively, in unsaturated zone (Bekele et al. 2011). It is
also stated that removal efficiencies are clearly defined for the particular infiltration
rate of recycled water and aquifer conditions. Carbonate configuration of aquifer
plays a major role to show the sorption mechanism of phosphate.
15.6 Challenges and Opportunities of Water Management
Some of the key issues which we are facing and which needs to be considered and
are evolving with time include:
Climate change: Previous studies and analysis show that there was not much fluctuations on hydrological management through climate change; but now, due to severe
drying and warm climate, there is lesser water availability. Initially observed data are
now not suitable to plan for variability in climate. It is mandatory to have information about how probability is affected by climate change so as to carry out risk-cost
analysis of alternative outlay in infrastructure required in the future.
Growth in urban demand: The population in urban areas is continuously growing
with the spread in urban areas thus placing pressure on water supply system to avail
the water for them. In recent decade, on globalscale, increase in percentage in water