Maximum Withdrawal & Terminal Lake
Flexibility is the game for all retirees. I have read several articles about the maximum sustainable withdrawal rate. Usually the rate is in dollars, sometimes adjusted for inflation. Since some of the basic living expenses are constant for the retired people, so the assumption for a relatively constant dollars term is reasonable. However, if flexibility in spending is incorporated in budgeting annual expenses, the retirement savings can last much longer.
We can learn from the nature about how to balance the evaporation from closed watersheds. A closed watershed is a basin where the river system drains itself to a terminal lake. The Owens River drains itself in to Owen Lake California is such a watershed. The Walker River terminates itself at Walker Lake is another example of such closed watersheds.
The amount of stream flow produced in Walker river basin is a variable. In wet years, there is a lot of water flowing into the Walker Lake, so the lake rises. When the lake rises, its surface water area increase, so does the evaporation from the lake. Since the annual evaporation rate has much less variation than the annual flow rate into the lake, so the lake size under natural conditions is relative stable. Over the last century, the economic activities in the Walker River basin have increased, so the amount of water diverted from the river has also increased. So the lake size has reduced tremendously.
In the Owens Valley case, since the amount of water diverted from the Owens River to outside the river basin (mostly to the Los Angeles Metropolitan Area) has increased so much. The Owens Lake is mostly dry now. Under natural conditions, Owens Lake was a perennial lake is a huge water surface.
For a terminal lake to keep its shape and size, the amount of water entering the lake should be balanced with the evaporation. If the amount of water entering the lake is reduced too much for extended period, then the lake goes dry.
If people learn from the natural system like the terminal lake basins, their retirement funds can last as long as they wish just like the nature had produced the beautiful Owens Lake and Walker Lake. However, human activities are so paramount to natural needs; the natural beauties of terminal lakes are replaced by the Hollywood stars.
We can learn from the nature about how to balance the evaporation from closed watersheds. A closed watershed is a basin where the river system drains itself to a terminal lake. The Owens River drains itself in to Owen Lake California is such a watershed. The Walker River terminates itself at Walker Lake is another example of such closed watersheds.
The amount of stream flow produced in Walker river basin is a variable. In wet years, there is a lot of water flowing into the Walker Lake, so the lake rises. When the lake rises, its surface water area increase, so does the evaporation from the lake. Since the annual evaporation rate has much less variation than the annual flow rate into the lake, so the lake size under natural conditions is relative stable. Over the last century, the economic activities in the Walker River basin have increased, so the amount of water diverted from the river has also increased. So the lake size has reduced tremendously.
In the Owens Valley case, since the amount of water diverted from the Owens River to outside the river basin (mostly to the Los Angeles Metropolitan Area) has increased so much. The Owens Lake is mostly dry now. Under natural conditions, Owens Lake was a perennial lake is a huge water surface.
For a terminal lake to keep its shape and size, the amount of water entering the lake should be balanced with the evaporation. If the amount of water entering the lake is reduced too much for extended period, then the lake goes dry.
If people learn from the natural system like the terminal lake basins, their retirement funds can last as long as they wish just like the nature had produced the beautiful Owens Lake and Walker Lake. However, human activities are so paramount to natural needs; the natural beauties of terminal lakes are replaced by the Hollywood stars.
posted by Unknown at 7:58 PM
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