The Indus basin hosts the biggest contagious irrigation network of the world (WAPDA 91). The basin provides key water and land resources of the country (Table 1) and has a level of maturity in the exploitation of these resources for agriculture with the help of an impressive river water conveyance and distribution network. Table 2 shows heterogeneous natural and climatic conditions and variable development characteristics of water use systems in the huge basin. The Indus Basin is a rich case to evaluate and understand the requirements of improved water management to address the challenges of increasing economic and livelihood pressures and sustainability threats. This analysis is based on a research study of the Indus Basin carried out from 1998 to 2003 (by the author). The objectives and characteristics of the designed systems have a determining influence on their functioning and performance. But there is an evolutionary process shaped by the responsiveness of different components within the boundaries determined by the potential and constraints of the systems. The evolved existing behaviour of the physical as well as management systems is a key to the future options and actions, defined and selected by the management approach. This article is organised in three sections describing briefly natural setting and planned character of the agriculture in the basin, actual behaviour of the irrigated agriculture and some of the future management options.

Major Drivers of Agriculture
The food and livelihood security, agriculture revenue and political control have been three driving elements behind the agriculture development in the Indus Basin for centuries. A variety of heterogeneous setups existed in the basin having different combination of these drivers. The agro-climatic and soil conditions provided varied natural agriculture potential while the socio-communal structure shaped different ownership, control and management relationships. Over a long historical period, Indian subcontinent had hundreds of states, tribes, kinship groups and small hamlets involved in agriculture and livestock near the supportive reaches of rivers, rain-fed areas, monsoon supported forests and grazing fields. These agriculture settings have survived despite strong central governments in India (Hugh 1928). The modern irrigation that started developing in the 18th Century has a continuity of the basic concepts, some new techniques, but variable priorities.

The water management and irrigated agriculture existed in the Indus basin for centuries. The urban infrastructure of the Harappan period (2500 BC) had water supply and sanitation facilities, the irrigated wheat and rice were grown. These systems were planned and operated by some state machinery. The Greek Ambassador Magasthene to the court of Emperor Chandar Gupta describes (330 BC) the control of irrigation facilities developed by the state (Michel 1967): 'he [a state official] measures land irrigated and water which is shifted into branches through a sluice'. He writes further about 'wealthy Indian farmers, who grow two crops a year. There grows throughout India much millet, which is kept well watered by a large number of streams. Almost all plains of the country have moisture drawn from rivers or rain'.

The revenue from agriculture in terms of crops and livestock, and the export of raw and refined agri-products can be traced back to 2000 years back in the Indus Basin. There is mention of rules to obtain water and pay a price for irrigation. The Land of the Five Rivers (Hugh 1928) quotes Arthashastra (a religious book dating from the Ram Chander's period 700 BC) from the Ancient Law by Maine H.S (1901), 'who irrigates by the manual labour pay 1/5th of the produce, for carrying water on shoulders 1/4th and by water lifts 1/3rd of the produce. The ‘superintendent’ of agriculture will grow ‘wet’ summer and winter crops depending upon the availability of water'. Abu Yasuf, the Qazi-ul-Qazat (Chief Justice) of Baghdad in the 8th century wrote a long history from Adam to his period (Moreland 1929). He mentioned the revenue rates in India as 2/5th and 3/10th in case of stream and Persian wheel irrigating wheat or barley, 1/3rd for gardens and dates, 1/4th for summer produce in areas under Muslim control.

With the development of state and administrative machinery, need to enhance the revenue and political control increased. In the 13th century, Feroz Tughlak built four canals, providing water to selected areas and introduced 'water benefit tax' called Haq-e-Sharb (meaning right to water). The Mughal King Akbar established a strong administration in India and supported local states to develop their water resources. His son, Emperor Jahangir (1605-1627) built the first perennial canal, Huslie, from the Ravi River near Lahore for the royal gardens. Another 110 km long canal 'Huslie' was built by Emperor Shah Jahan (1628 1658) for the Shalimar Gardens in Lahore. Both canals continued to exist and were improved by the Sikhs and British (Buckley 1905). ‘The assessment statements were prepared twice yearly for every villagea large army of clerks of the newly created Land Record Department was housed in a large record room at Fatehpur Sikri (Akbar's capital)’. He improved the land record system introduced by the Muslim ruler Tughliq 200 years ago. Two persons in a village were appointed to record the agri-land and assess the revenue, these ‘Qanoongo & Patwari still exists’ (Moreland 1929). The land was granted to individuals with titles indicating the measures of land (Jahangir's Durbar consists of Punj (5) and Dus (10) Hazarvi or thousands of acres). The tax rate during Akbar's period was 1/8th to 1/3rd with no tax on new cultivation for the first five years (Moreland and Ali 1918, Habib 1962). The Sikh Government in Punjab introduced an agriculture controlled by state administration and wealthy investors. They snatched land from the middlemen and title-holders of the Mughal period and distributed it to small cultivators without an ownership right. The agriculture revenue increased, and higher taxes were imposed on big owners, 2/5th to 1/3rd of the crop (Moreland 1929).

The trade of agriculture and food product with other Asian and European countries established the trade routes used by different invaders later on. 'The trade of spices, blue (colour) ivory, refined animal butter, silk, leather, handicrafts and precious metals to west Asia and Central Europe from the land and sea routes (Karachi) in 5th to 7th Century would have been an attraction to the warriors of these less fertile areas' (Extracts from District and State Gazetteers -- reprinted 1977). The export of rice, cotton, silk, spices, organic and animal butter is mentioned in Ian-e-Akbri.

The climate of the Indus basin needs canals irrigation. Buckley (1905): 'The chief inundation canals of India are found in the basin of the Indus and its five tributaries… Some of the inundation canals of Punjab lie in the high reaches of Sutlej and Jhelum but the majority of them on the areas bordering on the confluence of the rivers. The district of Multan, laying between Sutlej and Chenab, where rain hardly ever falls, is rendered beautifully fertile due to a series of inundation canals constructed by Mughal Emperor Aurangzeb (1680-90). In the Derajat on the right bank of the Indus, above Mithankot, there is a group of twelve canals. And Muzzafargahr, a corresponding group irrigates a tract of some 12 miles wide. The Upper Sutlej canals are in the central portion of the Doab lying between Ravi and Sutlej. Here the face of the country is covered with the farmer life and prosperity. More than fifty inundation canals existed in the lower Indus region in the mid-eighteenth century (Nazir Ahmed, Habib.Z 2004 ).

The British Period
Under the British Raj, a central authority was able to impose an administrative hierarchy over the whole territory for the first time in history. British realised the potential of agriculture to be a focal point for the rural country and economy. For the development during this period, the central investment and better technical solutions are much acknowledged factors, while political, administrative and economic interests are reported by the few: Theoborn (1905), Hughe (1928), Douie's Settlement Manuals (1899) & Gilmartin (1994).

The revenue was the key consideration when British administration started managing the agriculture sector. About 1/6th of the total revenue of Punjab was from the agriculture: 'Taxation was then levied almost entirely on the rural population. Practically the whole Punjab revenue, from largest head-land revenue-to the smallest-stamps comes from the producing masses while commercial classes escaped from taxation entirely' Hugh (1928). The first paragraph of Douie's Settlement Manual (1899) gives the basic principle of the land policy, 'the state has always claimed a share of the produce of the land from the person in whom it recognised a permanent right to occupy and till it or arrange for its tillage.' He also referred to an earlier law, the first clause of Regulation XXXI (1903): 'By the ancient law of the country the ruling power is entitled to a certain proportion of the annual produce of every beigha' (Douie 1899). Animal husbandry was a big industry, the Nomad tribes perceived rights to the forest and grazing fields without any title of ownership and they were rarely disturbed. Paying a regular tax on these grazing lands was even more difficult. So, it took time to implement a grazing tax per animal, of 0.1 Rs per goat to 1.5 Rs per camel or a buffalo. ( reprinted Gazetteer Mazafargarh). 'A god they apparently had. His name was political economy' (Thorburn 1904).

The first set of land ownership and revenue assessment laws was enacted around 1873. The process of 'irrigation colonisation' changed the structure of society in many areas, bringing scattered kinship groups and tribals under the influence of 'village colonies' having an administrative link with the British Government through the village gentry, lamberdar1 and patwari (revenue clerk). In this regard, the discussion on the establishment of Chenab colony is reflective in this regard. In 1891, the Revenue Secretary of the Punjab Government wrote to the center (District and State Gazetteers 1904): 'It seemed essential to preserve the tradition of Punjab as a country of peasants' farmers. No other general frame of society is at present either possible or desirable in the Province…. As already remarked, capitalist farming in general is not a system suitable to Punjab. But a moderate infusion of the capitalist element is not out of advantages. It supplies natural leaders for the new society; it gives opportunity to Government to reward its well deserving servants, and to encourage the more enterprising of the Provincial gentry; it attracts strong men who are able to command the services of considerable bodies of tenants; it furnishes a basis from which agricultural improvements may be hereafter extended, and, lastly, it enables Government to obtain a better price than might be otherwise possible for the ownership as distinct from the user of its land.' In 1892, allotment of land in Chenab colony was split as 40,000 acres to capitalists, 60,000 to yeoman (serviceman) and 27,000 to peasants.

Technical Character of Irrigation
The development of big river like alluvial canals, river structures to feed their head-works and a branched distribution system of each main canal feeding thousands of tertiary canals was the start of new era in the history of irrigation. In the Basin, first 50 years was the period of experimentation with the control structure of weir and design parameters of the 'regime alluvial canals'. A history of empirical relations exists for these developments based on the field experiments. For each new system, design parameters of the best performing canals were used as a reference. The later period was more focused on the design and alignment of self-regulatory tertiary structures to deliver 'equitable share' of water allocated to the command area of each watercourse. Many outlets structures have been designed and used in the basin to deliver 'close to the authorised discharge' under the expected flow variability. The key principle for the fair distribution in the upstream control non-regulated systems is to maintain the water level at the 'design target level' or proportionate to it. Hence, physical maintenance, operations of the main canal structures and regulatory procedures to ensure water levels became major responsibility of the organisation responsible for the canal water management. However, very little scientific contribution made in water and crop sciences during development phase of big irrigation schemes in the subcontinent could be quite puzzling for a reviewer of history.

Another dimension of empirical context was the selection of cropping patterns and water requirements for the design of secondary and tertiary systems. Agriculture was the main reference to calculate expected water requirements and cropping intensities. The systems developed in the beginning and sweet water areas had low water allowance, while contribution from the groundwater and rainfall was considered close to the prevailing irrigation. The river water available at a node and downstream commitment were the main constraints. Indus river had flows reduced to thirty per cent in winter, reducing the water levels as well in the river system. This shortage was addressed by making a fraction of the command area non-perennial (no water supply in winter) but with higher Kharif (summer) allocation. When the command area of a secondary canal was divided into perennial and non-perennial, the annual allocation was kept in the same range, providing double supplies to non-perennial in Kharif. No single formula was used for the perennial and non-perennial demarcation. The earlier canals were mostly perennial with a small percentage of non-perennial supplies to the rice growing areas having good rainfall (Jehlum, Chenab and Bari Doab canals). The rice and cotton dominant areas were mostly non-perennial with saline areas provided with perennial supplies. The canals developed at the later stage, some of them replacing flood irrigation through inundation canals, were made non-perennial because the perennial flows were already utilised. These areas were provided with very high water allowance at the pattern of flood irrigation. The water allowance of the canals generally increased with time as the development proceeded to the more arid area. An important influencing factor was capacity of the canals and the size of command areas to be benefited. During the British period allocation remained less than 3.5 cusecs for the perennial and less than 7 for non-perennial systems (even the arid areas like Sukkur barrage had 3 cubic feet/1000 acres).

The regional interest to get maximum supplies had greater influence in the areas owned by independent states and the lower Indus. The exceptionally high allocations to the Guddu and Kotri barrage systems (started operating in 1956 and 1962 with 9 to 17 cusecs per 1000 acres) are due to high aridity, saline groundwater, rice irrigation and availability of river flows for summer only. The design discharge is not used in most of the high allocation canals. Different estimates of the crop water requirements and seepage losses are given by different project studies (LIP 1965, WISP 1978). The river diversions include water supplied to lakes, local structures for the drinking water and infrastructure like railways. For the water sharing negotiation, main canals have been getting out of debate after 1991, as WAA fixes provincial water share with the statement: 'the provinces will be responsible for the internal distribution'. The distribution at the main canal level is highly inequitable (Kijne 1994, Habib, Kuper 1998), this inequality is accepted by WAA by making 1978-82 actual supplies a reference. No forum is officially available to check or rectify water distribution at the main canal level.

The Administrative Model
The basic character of administrative and institutional setup adopted at the design stage has sustained till today and closely influenced the way changes are addressed in irrigation and water management. Some important factors behind this robustness are briefly discussed:

Central planning: The development and allocation of river water resources was planned at the central government level in India. The provinces and independent states were asked to submit the proposals, which were finalised by the special commissions formed by the central government.

Minimum management input: The irrigation systems were planned and designed to have minimum managerial input. The regulatory structures were kept minimum on the primary and secondary network. All tertiary head-works were self-regulatory and farmers were responsible for the maintenance of watercourses. The department was made responsible to monitor some of the responses of irrigation like drainage as a separate activity. Given the size of irrigation infrastructure, heterogeneity of the seasonal water rights, operation and maintenance (O & M) was defined with clear and authoritative rules and roles (Manual of Irrigation Practices 1873).
Public works Operations: The provincial public works departments were responsible for the operation and maintenance of the systems like other public utilities, roads, railway, etc. Originally the 'irrigation wing' of the public works and later-on independent Provincial Irrigation Department was not concerned with overall water management or other uses of water.

Committed performance targets: In setting the targets, irrigation delivery can be considered like a service oriented public utility. However, nature of the utility was such that targets could only partially be achieved and it was very difficult for the user to evaluate this service. It is the responsibility of the department (service provider) to monitor and evaluate its own functioning. The users can claim a remedy in case of production failure.

The empirical evidence, simplicity and administrative control were three characteristics of the water resources management in the Basin. The 'new irrigated agriculture setup' had few inherited dichotomies (Michel 1967, Gilmartin 1994). The development objectives of the British Indian Government during the earlier and the later periods changed, which resulted into a big difference in water allowance, land tenure and ownership. Famine control and rural settlement2 were the main objectives during the first phase of the development of the North Indian irrigation schemes (Jurriens and Mollinga 1996), while the colonial government's investment in the second phase was more focused on revenue generation through the sale of crown wasteland and the encouragement of cash crops. The conflict between the engineering need to implement an 'appropriate technology' and the administrative interest of the colonial government to develop and facilitate a rural 'loyal elite' could not be resolved by the straightforward irrigation laws enforced by the Canal and Drainage Act of 1873. The hydraulic efficiency of water supply and the economic efficiency of water utilisation did not always match (Michel 1967, Lieftinck 1968).

From Run of the River to a Regulated Basin
The Indus Waters Treaty between India and Pakistan in 1960, and the construction of two big reservoirs (Mangla 1967, Tarbela 1978) enhanced the inter-connectivity and inter-river water transfer potential to a very high level. It is unique that the major sub-basins of three big rivers having about 6 million hectare irrigated land had to rely on water transferred from other rivers. The net increase in diversions is about 60 per cent after 1960 ( bcm to bcm - Habib 2004) . The Indus network is the same today as it was in1978. All main canal headworks are linked through rivers and link canals, reservoirs supporting whole system other than the 1st barrage of the Chenab river. Sharing the reservoir is a fully regulated system for release of water. Even to feed all canals with fair share from the direct river flows, each structure on the main network would need to be operated. This is a basic change in the designed run of the river supply based water delivery network.

Water Allocation and Division Principles
With the design of large-scale canal systems, the surface water availability changed from an 'access control' to an 'authorised allocation'. The concepts of 'riparian water rights' and 'prior water use rights' facilitated the access of 'old users' to a limited level, but became obsolete when all ‘divertible water’ got engaged with the 'authorised allocation'. With the extension of irrigation, the probability of having lower than the allocated water during low supply period of early and late Kharif (summer) increased. This shortage was distributed among the canals through operational priorities, which increasingly becomes tougher and an issue of disagreement among the provinces. All water allocation committees between 1937 and 1982 (Andersons, Sindh-Punjab draft, Haleem commission, etc.) had to address the priority-issue, but none of the draft agreement were fully accepted by the provincial irrigation departments.

The flexibility provided by the reservoirs relaxed the priorities and decreased the shortage of the authorised allocation, and put a new challenge to share the stored water. The highest demand on this water was during the high stress period. This affected the doctrines of 'equitable distribution' and 'perennial and non-perennial' division. More water could be supplied in Rabi (winter) than officially allocated. An operational technique was to distribute this water through the scheduling of available excess or shortage. By virtue of the regulation process, scheduling has to be responsive to the water demand of different canal commands during the period of interest. Eventually, the non-perennial canals started getting water in Rabi (winter) without any command areas allocation or the distribution formula, regulated through the 'historical diversions'. The differences on the interpretation of WAA (1991) started surfacing as early as 1994 and continue till today. WAA weaknesses are as follows: