The decentralized nature of groundwater use

In addition to being invisible, groundwater is a 'horizontal' resource (in spite of the verticality of wells that abstract groundwater from aquifers), i.e. farmers located above an aquifer can sink wells independently of each other over a significant areal extension depending on the size of the aquifer. For example, in Mexico some aquifers have an area of only a few square kilometres, whereas the Guarani aquifer system in South America has an area of 1.2 million square kilometres, i.e. the size of England, France and Spain combined (World Bank, 2003).

Therefore, groundwater as a resource - in a situation of abundance - is distributed in an equitable manner to those above a given aquifer. With the less-pronounced upstream-downstream dimension, which is so defining in surface water management, and where upstream users literally have the upper hand over downstream users, the groundwater management challenge is a radically different one. The key issue is to manage a pool resource, which any user who can afford a deep enough well has access to and which therefore can provide benefits to many, but with the focus to make it last for as many users as possible for as long as possible. Groundwater management therefore implies dealing with decentralized stakeholders who will make their decisions based on private utility, weighing their costs (sinking the well, variable abstraction costs, etc.) and their benefits (well yields, type of use, benefit derived from it, etc.). Compared to surface water management, there is no 'tap' in the form of a reservoir release or an irrigation gate intake that can control water access.

The management challenges vary, of course, from country to country and between regions within countries. The manageability of groundwater will depend on the size of the countries and of aquifers, aquifer yields, storage capacity, population density and abstraction for agriculture (since agriculture is usually the primary purpose with the largest number of users, it will have the most impact on management challenges) (Table 8.1).

The categories shown in Table 8.1 only serve as abstracts and in practice assessments will differ. Aquifers vary not only in their spatial dimensions, but also in their yields and recharge profiles. Just so do groundwater users differ, and sociopolitical settings, which influence institutional options for aquifer management, will diverge as much as aquifer characteristics. Aquifer management strategies will therefore have to be developed accordingly. The key point is, however, that the more the actors need to be involved and monitored and the more the abstraction is compared to yield, the higher will be the transaction costs to devise and implement institutional arrangements for aquifer management, and therefore the bigger the challenge to manage the aquifer in a sustainable manner.

The need for groundwater management instruments changes over time. As illustrated in Fig. 8.2, there is a logical progression to groundwater management needs (also compare with Fig. 2.5 by Shah, Chapter 2, this volume).

The figure depicts a typical curve for aquifer management needs, ranging from the baseline situation where groundwater is abundant compared to abstraction to a high-stress situation where abstraction has turned excessive and is leading to irreversible aquifer deterioration. While many will agree that groundwater management is needed in the high-stress situation in order to return to the more

Table 8.1. Management implications for some types of aquifer-groundwater user relationships.

Low density of agricultural

High density of agricultural

groundwater users and

groundwater users and high

low abstraction rate

abstraction rate compared to

compared to recharge

recharge

Small/medium aquifer Low transaction costs in

Medium to high transaction

developing and enforcing

costs to institute groundwater

institutional arrangements

management, but probably

for groundwater

manageable due to small

management; few

areal extent of intervention

instruments (e.g.

needed; however, need for

monitoring network)

groundwater management in

needed

order to ensure sustainability

Example: many aquifers in

Example: some Mexican

sub-Saharan Africa

aquifers

Large/extensive aquifer Possibly higher transaction

If extensive, major aquifer:

costs in developing and

Very high transaction

enforcing institutional

costs to institute effective

arrangements for

groundwater management,

groundwater management

both to achieve agreement

due to spatial distribution;

on the institutional framework

but few instruments

and to enforce and monitor

needed while abstraction

Example: North China Plain

remains low

If extensive, but low-

Example: Guarani aquifer

permeability aquifer:

system

High transaction costs due to

high density of users; but low

transaction costs because

aquifer could be managed as

local units

Example: Indian basement

stable development situation, we clearly face a paradox here. As can be seen in the figure, groundwater management instruments would ideally be employed at any stage of aquifer use. Even in the baseline situation, registration of abstraction wells and springs as well as source mapping are highly recommended, given that transaction costs for doing so are much lower in a situation of few users and sustainable abstraction than in a later stage when stress has set in. A simple network with a number of monitoring points would also provide important information. For instance, the state of Maharashtra, India, has been monitoring groundwater for 30 years. While the groundwater situation 30 years ago probably would not have triggered major concerns, the long-term investment in the monitoring network and data collection is now paying off because the data series provides important information, even if not sufficient to resolve the serious overabstraction problems

Sustainable level of resource development with acceptable impacts under present condition

Time (artillery scale)

0: Baseline situation

Availability and accessibility of adequate-quality groundwater greatly exceed small dispersed demand

Registration of abstraction wells and captured springs required, together with maps of occurrence of usable

Incipient stress

Growth of aquifer pumping, but only few local conflicts arising between neighbouring abstractors

Simple management tools (e.g. appropriate wellspacing according to aquifer properties) should be applied

Significant stress

Abstraction expanding rapidly with impacts on natural regime and strong dependence of various stakeholders on resource

Regulatory framework needed, based upon comprehensive resource assessment with critical appraisal of aquifer linkages

3A: Unstable development

Excessive uncontrolled abstraction with irreversible aquifer deterioration and conflict between stakeholders

Regulatory framework with demand management and/or artificial recharge urgently needed

3B: Stable highly developed

High level of abstraction, but with sound balance between competing stakeholder interests and ecosystem needs

Integrated resource management with high level of user self-regulation, guided by aquifer modelling and monitoring

Fig. 8.2. Stages of groundwater resource development in a major aquifer and their corresponding management needs. (From World Bank, 2002-2004.)

resources managers now face. Regrettably, such basic steps to start building a future aquifer management system are usually not taken. One region where the option still exists is sub-Saharan Africa where groundwater is still abundant in many areas but where development requires scarce financial and human resources to meet many other needs. If action is not taken, once significant stress begins to show and crucial information about users and aquifer yields is required, it may not be available. One possible solution is to improve capture of information already collected. The groundwater development projects in place in many countries in the region generate substantive insight among the drillers and diggers, and the information they create could very well be captured to provide baseline information about aquifers and aquifer users.

Many countries that have not invested in collecting and systematizing such information start only after major aquifer stress appears with the basics, such as well and user registration, measurement or estimation of groundwater abstraction and definition of an entitlement regime, rather than being able to focus on management and fine-tuning of instruments. This way, much valuable time is lost and in many cases it is already too late.

While this chapter primarily focuses on the challenges posed by overab-straction, it is recognized that there are a number of regions in the world where groundwater still constitutes a resource to be further developed. Differing examples are presented in discussions on South Asia (Shah et al., Chapter 11, this volume) and Central America (Ballestero et al., Chapter 6, this volume). As pointed out by Shah et al. (2000): '[C]entral to appreciating the global groundwater situation . . . is the coexistence of regions with undeveloped resources and those with overdeveloped resources, and the socioeconomic dynamic that has relentlessly impelled the former to shrink and the latter to expand.'

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