Dear Nature Lovers,
A very happy new year to all of you !
Its 13th year of sending out desktop calendars ! Big Thanks to You for supporting this desktop calendar campaign and being inspiration for the same.
This year we bring a new theme - RIVER ECOLOGY.
Through 12 months we will depict entire journey of a river starting from its SOURCE region in the hills, flowing through the PLAINS and reaching sea at its MOUTH or DELTA region. Every month we will have one physical or biological aspect of river, with a short commentary from an ecological perspective.
River has two main characteristics : FLOW and FLOOD.
First calendar focuses on RIVER FLOW.
River flow collects water from precipitation through its catchment or drainage basin from surface runoff or the release of stored water in natural ice and snow peaks i.e. glaciers and groundwater seepage. Rivers or streams, those flow only periodically, in response to rains or seasonal snowmelt events are called ephemeral or intermittent streams.
There are various perspectives to look at this flow and various terms are coined to state its functions and importance. Those are :
Base Flow : The portion of stream flow which is not runoff. This is seepage of water from the ground into the channel, also called base flow. This flow could be significant enough to allow the river or stream to flow year round making it perennial. This flow is governed by hydro-geology of the catchment of the river. Further it is important to note that any alteration in the land use of the catchment affects the river flow. So for managing base flows, it is important to consider the hydro-geology of catchment.
E-flows : Environmental flows , is the quantity, timing and quality of water flows required to sustain freshwater and estuarine ecosystems and the human livelihoods and well-being that depend on these ecosystems.
Ecological flow Or Minimum Flow : The flow regime linked to biota of a river can be called as Ecological Flow. Rather than simply allocating a minimum low flow, it has long been accepted that to maintain the ecological integrity of rivers, flow regimes need to incorporate natural variability, including aspects related to the magnitude, frequency, duration, timing and rate of change of flows.
All these perspectives are critocal to maintain healthy rivers. However, the world's rivers are increasingly being altered through the construction of dams, diversions, and levees. Rivers worldwide are under increasing threat from hydrologic alteration. Managing the environmental and ecological flows is one way of dealing with this !