Agriculture Reference
In-Depth Information
the sum of the amounts consumed by rival offstream uses which have a
priority over that activity. In any event, any user can apply more water than
the allotment established in its water right. This last aspect justifies that
initial minimum option of restrictions 11.2 to 11.6. Given that we have two
systems, the variables in
j+1
and
j-1
are null for
j=2
and
j=1
, respectively.
The spatial structure is also implicit in the restrictions,
i.e.,
between two users of the same type, the user which is located further
upstream will have priority. Furthermore, the state variable takes into
account all the requirements located downstream. Thus, the demands of
system 2 condition the available reserves in the whole system at any given
time.
As we can note, the level ofjoint profit depend both on the volume
of supply of water and on the time and spatial structure of the water rights.
More detailed information about the behaviour of reserves and joint profit
function for different availability of water can be obtained from the authors
upon request.
On this basis, we are in a position to carry out a comparative
analysis with the following steps. First, we define a starting point situation
according to which, for the sake of simplicity, the supply and the
requirement coincide exactly in space and time. This is the situation that
arises in the case where the supply of water is exactly that necessary in
order to satisfy all the water rights under the terms and in the places
established. Secondly, we suppose a change in the initial conditions in two
directions: a fall in water supply (drought) and an increase in agricultural
requirements. We then evaluate and compare the two allocations, namely,
that resulting from the strict application of the current water rights and that
resulting from the joint profit optimisation exercise.
3. APPLICATION OF THE MODEL TO A CASE STUDY
In this Section we apply the model in order to represent and solve two
specific water allocation problems. Our case study rests on two types of
data: that of system 1, which is real and has served to calibrate the model,
and that of system 2, which is simulated.
3.1. The starting-point situation
The starting data for system 1 come from the Vadiello reservoir, located in
North-eastern Spain. The requirements are well delimited in this area, as
can be seen from Figure 11.3. Data about these requirements were obtained
from CHE (2000) and MAPA (1999). Furthermore, the security reserves
for urban use are 5 and
respectively, in each system, whilst the
Search WWH ::
Custom Search