Water Resources Assessment at Piracicaba, Capivari and Jundiaí River Basins: A Dynamic Systems Approach

Abstract

The Piracicaba, Capivari, and Jundiaí River Basins (RB-PCJ) are mainly located in the State of São Paulo, Brazil. Using a dynamics systems simulation model (WRM-PCJ) to assess water resources sustainability, five 50-year simulations were run. WRM-PCJ was developed as a tool to aid decision and policy makers on the RB-PCJ Watershed Committee. The model has 254 variables. The model was calibrated and validated using available information from the 80s. Falkenmark Water Stress Index went from 1,403 m^sup 3^ person^sup -1^ year^sup -1^ in 2004 to 734 m^sup 3^ P^sup -1^ year^sup -1^ in 2054, and Xu Sustainability Index from 0.44 to 0.20. In 2004, the Keller River Basin Development Phase was Conservation, and by 2054 was Augmentation. The three criteria used to evaluate water resources showed that the watershed is at crucial water resources management turning point. The WRM-PCJ performed well, and it proved to be an excellent tool for decision and policy makers at RB-PCJ. [PUBLICATION ABSTRACT]

Water Resour Manage (2010) 24:761773 DOI 10.1007/s11269-009-9470-x

Water Resources Assessment at Piracicaba, Capivari and Jundia River Basins: A Dynamic Systems Approach

Rodrigo Mximo Snchez-Romn

Marcos Vinicius Folegatti

Alba Mara Guadalupe Orellana Gonzlez

Received: 10 December 2008 / Accepted: 9 June 2009 /

Published online: 25 June 2009 Springer Science+Business Media B.V. 2009

Abstract The Piracicaba, Capivari, and Jundia River Basins (RB-PCJ) are mainly located in the State of So Paulo, Brazil. Using a dynamics systems simulation model (WRM-PCJ) to assess water resources sustainability, ve 50-year simulations were run. WRM-PCJ was developed as a tool to aid decision and policy makers on the RBPCJ Watershed Committee. The model has 254 variables. The model was calibrated and validated using available information from the 80s. Falkenmark Water Stress Index went from 1,403 m3 person1 year1 in 2004 to 734 m3 P1 year1 in 2054, and Xu Sustainability Index from 0.44 to 0.20. In 2004, the Keller River Basin Development Phase was Conservation, and by 2054 was Augmentation. The three criteria used to evaluate water resources showed that the watershed is at crucial water resources management turning point. The WRM-PCJ performed well, and it proved to be an excellent tool for decision and policy makers at RB-PCJ.

Keywords Water stress Water management Watershed Modeling

1 Introduction

Water problems are extremely complex due to different points of view and interests, such as: (a) Rural people are direct water consumers, while urban people get water

R. M. Snchez-Romn (B) M. V. Folegatti A. M. G. Orellana Gonzlez

Department of Rural Engineering (LER), Universidade de So Paulo, Campus Luiz de Queiroz (ESALQ/USP), Av. Pdua Dias 11, Agronomia, Piracicaba, 13418-900, So Paulo, SP, Brazile-mail: [email protected]

M. V. Folegattie-mail: [email protected]

A. M. G. Orellana Gonzlez e-mail: [email protected]

762 R.M. Snchez-Romn et al.

through suppliers; (b) Water issues are related to income; (c) Water shortages are perceive differently, according to individual consumption; (d) Water issues are quantitatively and qualitatively uneven in time and space within a basin; and (e) Water is an essential resource for life and society. Therefore, increasing interest in its conservation and correct use is developing. There are many perspectives, interests, perceptions and alternatives for use of water resources due to the diversity of people involved and their social status, occupations, income, priorities and locations.

Water resources management should be linked to environmental sustainability, which is a function of the growth of each component in the watershed. Considering that agriculture is responsible for food production and large volumes of water consumption, it is a key point in our analysis. A populations income growth implies a substantial increase in the demand for water and food as well as an increase in the contamination of bodies of water.

Then, questions arise, such as: Up to what point it is possible to maintain the growth of productive activities in diverse areas of the economy and still satisfy the growing demands of the population without harming water resources sustainability? What level of river basin development are Piracicaba, Capivari, and Jundia watersheds at (RB-PCJ)? Is irrigation sustainable at RB-PCJ? These are important questions to be answered by the assessment of water resources at RB-PCJ using the Water Resources Model for the Piracicaba, Capivari, and Jundia River Basin (WRM-PCJ). In Brazil, the RB-PCJ is part of the Water Resources Policy lead by the National Water Agency (Agncia Nacional de guas), which is responsible for implementing and articulating the connections between the management of the River Basin Committees (RBC) and taxing all of the federal water resources.

A direct relationship exists between water resources and the systemic approach because both are systemic and non-linear (Ohlsson and Turton 1999). The basic principle of any systemic study is connectivity. A system is a set of elements with connections amongst themselves and their environment. Each system is composed of subsystems that are all part of a larger system, with each one being autonomous and simultaneously open, directly interrelated and integrated with its environment (Santos 1982).

The systemic approach is used in water resources management to analyze and improve systems. The units that belong to a water resources system are part of a dynamic and complex system, where many activities and explorations coexist and interact. Each activity has inputs, such as labour, power, capital, etc., and outputs, such as agricultural goods, residues, agricultural and industrial contaminants, etc. (Costa 1993). However, water resources sustainability should be linked to the users capacity to conserve or increase quality of life; maintaining and guaranteeing those resources for future generations, also known as adaptive capacity (Turton 1999).

The Dynamics System (DS) methodology is based on and derived from the Theory of Control developed by Forrester (1961). The fundamental principle of this methodology is that every dynamic behavior is a consequence of the system structure (POWERSIM 1996). It is characterized by changes happening along the time.

DS simulation models are real world abstract descriptions. They represent complex problems and are characterized by their dynamics, none-linearity, feedback relationships and discrepancies in time and space (Wiazowski et al. 1999). A DS model should capture only the essential factors of a real system and disregard all the other factors. The main use of the model is to communicate a point of view on

Water Resources Assessment at Piracicaba, Capivari and Jundia 763

specic problems. It does not try to be the reality but to be as close as possible to it and to predict its behavior (Perez Maqueo et al. 2006). The user should always be conscious of the limitations of the model he/she is using.

When focusing on a problem, there are several ways to use simulation models. The objectives that guide the WRM-PCJ construction dene its structure. With this in mind, and based on other countries experiences and other watersheds development trends, a DS simulation model was developed and run. This model intended to dene an up-to-date RB-PCJ development stage and to assess water resource availability and agriculture sustainability for the next 50 years.

2 Materials and Methods

WRM-PCJ uses object-oriented DS on a STELLA 9.0 platform. The model relates environmental, physical, social and economical elements to explain the dynamic behavior of water resources that are offered and demanded and wastewater generated by using several existing consumers in RB-PCJ. The model is a tool to aid policy makers and decision makers to nd different alternatives to manage water resources at RBC-PCJ.

To analyze the impact of water resource sustainability due to water offered and demanded, WRM-PCJ uses: the Sustainability Index (Xu et al. 2002), which denes the relationship between total consumption and total available water, and the Falkenmark Index (Falkenmark 1989; Falkenmark et al. 2007), which relates use-to availability (Level of exploitation) and the number of people who have to share an unit of water (water shortage).

When analyzed water resources use to available water ratio through time, river basin development phases proposed by Keller et al. (1998) were considered. These development phases characterize the development, or management, stage at which the watershed is. This information is important to establish water demand trends, which is valuable information for decision and policy makers to take adequate measures to guarantee water resources sustainability.

2.1 Consumer Water Demand

Water demand was dened based on in situ studies of water consumption habits in the area. All information was collected and presented in several Water Resources State Plans, many secondary information sources linked to agencies that support productive sectors, and by the water resources administration (PERH 2004, 2005; SIRGH 2007; SABESP 2007; DAEE 2007; IEA 2007; UNICA 2007; IBGE 2007; IPEA 2007; INPE 2007; INMET 2007).

To be effective and precise when modeling irrigated agriculture and animal breeding, it is necessary to have a detailed knowledge of water consumption and wastewater generation. To do this, it is necessary to conduct a water user census, with detailed information on water habits. The lack of information on these topics created some uncertainties during the simulations.

Regarding ecological ow, several methodologies were considered to dene a value for the simulations. It was decided to use the smallest value that could be

764 R.M. Snchez-Romn et al.

computed. This consideration was based on the fact that the ecological ow value should be a decision taken at the RBC-PCJ; but the concept of ecological ow is introduced for the rst time at the RB-PCJ water demand balance. A French method for existent water systems uses a value equal to 1/40 of the average daily ow (Souchon and Keith 2001). According to PERH (2005), the average daily ow for RB-PCJ is 64 m3 s1. Therefore, the ecological ow used during the WRM-PCJ runs was 1.6 m3 s1 for four scenarios, and 19.6 m3 s1, for a sensibility analysis, for one scenario representing 30% of the average daily ow, a more usual value used for ecological ow (Falkenmark et al. 2007).

2.2 Study Area Characterization

Three watersheds form the RB-PCJ system, known as Water Resources Management Unit 5 (UGRHI-5), were studied. This unit includes 64 municipal districts, 60 belonging to the State of So Paulo and four belonging to the State of Minas Gerais (PERH 2005). RB-PCJ has a total area of 15,414 km2.

The three rivers (Fig. 1) ow toward the Tiet River and belong to Rio Tiet River Basin. The estimated population at UGRHI-5 in 2004 was 4,434,937 urban inhabitants and 223,998 rural inhabitants (PERH 2005). The main economic activities are: industry, agriculture, agro industry, mining, recreation and landscaping, and commerce and services. By 2005, the RB-PCJ was responsible for the production of5.8% of Brazils GNP.

2.3 Water Resource Systems Structures

Figure 2 is the causal diagram of the water resources system structure that was modeled to analysis the water resources sustainability at the RB-PCJ study area.

Fig. 1 Piracicaba, Capivari and Jundia River Basins (source: PERH 2005)

Water Resources Assessment at Piracicaba, Capivari and Jundia 765

Fig. 2 Causal diagram for the

Piracicaba, Capivari andJundia water resources system

The Water Offer variables are: surface water and groundwater; both variables guarantee the Water Stock from where water is drawn by consumers. Water Demand is the sum of the water demands from the population, environment, agro industry, animal breeding, industry, and agriculture.

2.4 Piracicaba, Capivari and Jundia River Basins Water Resources Model (WRM-PCJ)

WRM-PCJ is an explicit dynamic simulation model developed to simulate the RB-PCJ water resource system. The WRM-PCJ has 254 variables in 11 sectors; these sectors can be grouped as: demand, offer, and specic computations. The demand sectors are: Agriculture, Animal Breeding, Agro-industry, Environment, Population, and Industry. The Offer Sector has surface water and groundwater to offer as a product of annual precipitation, a variable that can change annually. The Computation Sector includes: Wastewater Returned Volume, Total Water Demand, Water Allocation Incomes, and Equivalent Population.

The water balance equation (1), at RB-PCJ expressed as a nite-difference equation in WRM-PCJ, is:

BalanHidric (t) = BalanHidric (t dt)

+ [parenleftbig]SUPPLYVol_Water_exit_BHPCJ-Total Consumption PCJ[parenrightbig]

dt (1) where BalanHidric(t) is the Water balance for year t (m3 year1); SUPPLY is the

Water Offer for year t (m3 year1); Vol_Water_exit_BHPCJ is the Water Volume that runs off Piracicaba, Capivari and Jundia Watershed Basin (m3 year1); and, Total Consumption PCJ is the Total Water Demand by consumers at Piracicaba, Capivari and Jundia Watershed Basin (m3 year1).

The water offer (2), total consumption (3), use to availability (4), water per capita available (5), water shortage (6) and sustainability index (7) equations in WRM-PCJ are:

OFFERT = Total_Runoff_Vol + Total_Inlt_Vol (2)

Total_Consumption_PCJ = VTRAG + VTRAI + VTRamb

+VTRInd + VTRpop + VTRPEC

+ (Demanda_RMSP 86400 365) (3)

766 R.M. Snchez-Romn et al.

Use2Av = 100 [parenleftbig]1 [parenleftbig]Total_Consumption_PCJ[slashbig](Runoff_Vol + Inlt_Vol)[parenrightbig][parenrightbig]

100 (4)

WatPerCapAva = (Runoff_Vol + Inlt_Vol)[slashbig][parenleftbig]Rural_Pop + Urban_Pop[parenrightbig] (5)

Water shortage = 1 106[slashbig]WatPerCapAva (6)

Sust_Index = WaterBalan[slashbig]OFFERT (7)

where OFFERT is total water volume available at RB-PCJ (m3 year1); Total_Runoff_Vol is total runoff water volume produce by precipitation (m3 year1); Total_Inlt_Vol is total water volume that inltrates (m3 year1); VTRAG is total water volume consumed by agriculture (m3 year1); VTRAI is total water volume consumed by agroindustry (m3 year1); VTRamb is total water volume committed to environmental ow (m3 year1); VTRInd is total water volume consumed by industry (m3 year1); VTRpop is total water volume consumed by urban and rural population (m3 year1); VTPEC is total water volume consumed by animal breeding (m3 year1); Demanda_RMSP is total water volume diverted to So Paulo Metropolitan Area, usually is 31 m3 s1 (m3 year1); Use2Av is a ratio between total water consumption and total water volume available, also known as water use or as use-to-availability (%); WatPerCapAva is a ratio between total water volume available and total population living at RB-PCJ (m3 person1 year1);

Water shortage is the ration between a hydrological unit (106 m3) and water per capita available; Sust_Index is the ratio between water balance and water offer (unitless); WaterBalan is OFFER Total_Consumption_PCJ.

Figure 3 represents the water resources offer structure linked to the Water Offer Section at the study area as proposed in WRM-PCJ.

Here, the variable water offer is SUPPLY (106 m3 year1 = Mm3 year1), and

it represents precipitation volumes that became runoff volume (Vol Runoff Tot) or percolated and inltrated volume annually (VolInfTot). Additionally, all return waters (VolAReturn) are also considered to be water offer. All these volumes are in Mm3 year1. The use-to-availability (Use2Av) is also known as Water Resources

Vulnerability Index by Raskin et al. (1997), and it is used in the graphic proposed by Falkenmark et al. (2007) as the y-axis (Fig. 5).

2.5 Model Validation and Calibration

Model validation has to consider models internal logic and structure (Ruth and Hannon 1994). To study the real behavior of a system it is necessary that the model reproduce systems behavior (Forrester 1961; ITHINK ANALYST 1997; Grcic and Munitic 2005; Sterman 2005). Simulation model validation is judged by its usefulness and convenience (Forrester 1980). Simulation models validation is the demonstration that its formal conceptions are correct; in other words, that the code and mathematics are mechanically correct. The calibration is the evaluation and adjustment of models parameters and constants to t real initial data and simulated results (Rykiel 1996).

For the purpose of parameter estimation, the calibration period from 1980 through 2020 is showed in Fig. 4. This gure shows predicted population by RELATORIO 0 (1999) and by WRM-PCJ. The population predicted by the model WRM-PCJ when

Water Resources Assessment at Piracicaba, Capivari and Jundia 767

Sector Water Offert

Wstwat Return Vol

Runoff Vol

Infilt Vol

Rural Pop

Runoff Coef

Runoff Vol WatPerCapAva

Total Runoff Vol

Runoff

TotRunoffVol exit

Use2Av

Sust Index

Urban Pop

Annual Mean Rainf

WaterBalan Total Vol Req PCJ

Climat Chang Fact

Total Consumption PCJ

OFFERT

Watershed Area

Infilt

Vol Water exit BHPCJ

exitVolInfTot

Total Infilt Vol

Infilt Vol

Infilt Coef

Fig. 3 Water offer sector represented by the Piracicaba, Capivari and Jundia River Basins Water Resources Model (WRM-PCJ) (Snchez-Romn et al. 2008)

compared with the one computed in RELATORIO 0 has a difference of 0.9%, which are nearly same. Similarly, domestic water demands for the same period are not quite different since follow population trend. Obviously, industrial sector development and the progress of the economy throughout river basins will increase gradually the percentage of water demand for industrial and domestic use, at the same time as demand for agriculture water will decrease.

Due to comparing real and computed data from the 80s to 2020 at RB-PCJ, the simulation model proposed here was validated, calibrated and evaluated. The model is suitable to characterize the internal relationships at the hydraulic system at Piracicaba, Capivari and Jundia river basins.

Fig. 4 Population forecast from 1980 through 2020

768 R.M. Snchez-Romn et al.

Table 1 Parameters used to create the ve simulation scenarios

Parameter Unit Scenario

1 2 3 4 5

Time step Year 1 1 1 1 1 Time frame Year 50 50 50 50 50 Precipitation mm year1 1,460 1,314 1,168 1,460 1,460

Irrigated area

At 2004 ha 26,468 26,468 26,468 26,468 26,468 At 2054 ha 57,571 57,571 57,571 42,914 57,571 Growing rates

Population % 1.4 1.4 1.4 1.4 1.4 Manufacturing industry % 1.5 1.5 1.5 1.5 1.5 Food and beverages industry % 1.5 1.5 1.5 1.5 1.5 Power generation industry % 1.5 1.5 1.5 1.5 1.5 Cellulose and paper industry % 1.5 1.5 1.5 1.5 1.5 Sugar and alcohol industry % 1.5 1.5 1.5 1.5 1.5 Environmental ow m3 s1 1.6 1.6 1.6 1.6 19.2

Flow diverted to Sao Paulo m3 s1 31 31 31 31 31 metropolitan area

2.6 Simulation Stage: Application of the Dynamic Simulation Model

Five runs within a 50-year time frame were performed. Scenario 1, Business as UsualBaUwater consumption and wastewater generation rates of existent consumers were maintain with no changes, using a time step of 1 year, and precipitation equal to the mean value, 1,460 mm year1 (IRRIGART 2004), throughout the simulation. Scenario 2 considers a 10% reduction in precipitation due to climatic changes (CC), without variations in all other variables. Scenario 3 considers a 20% reduction in precipitation due to CC, without variations in all other variables. Scenario 4 considers the total irrigated area to stop growing in year 2020, without variations in all other variables. Scenario 5 considers the conditions set in scenario 1 and an ecological ow equal to 19.2 m3 s1 (Table 1).

3 Results and Discussion

It was observed from computed values that, for the 50-year simulation period, for the BaU scenario in RB-PCJ, an increment of approximately 76% of the total water demand in the study area should be expected. Additionally, for the BaU scenario, in 2004, total consumption represented around 74% of total available water volume without considering reused waters; by 2007, it goes up to approximately 82%, and, by 2024, it is expected that RB-PCJ will become a closed basin for two years (Fig. 5). Consumption changes foreseen by PERH (2004) produce changes in water demand conditions, for about 6 years in the basin; but these do not prevent the permanent closing of the basin in any scenario. Therefore, to supply new consumers reuse water will become the available water source.

Water Resources Assessment at Piracicaba, Capivari and Jundia 769

Fig. 5 Use-to-availability for

Piracicaba, Capivari andJundia River Basins estimated using the Piracicaba, Capivari and Jundia River BasinsWater Resources Model (WRM-PCJ) for a 50-year time frame simulation with ve scenarios

Wastewater reuse will increase the water offer, but the necessary water volume to guarantee water dilution and the sustainability of the water bodies will be under stress since more wastewater reuse will become a water source for human activities. Without any doubt, this situation will increase water treatment price, and alternative measures to solve this situation are a must. New wastewater treatment plants should be built since it is expected that the total load will increase up to approximately 93% by 2054, in the BaU scenario.

For the BaU scenario and 50-year simulation timeframe, the water demands increase up to 24% by 2030, compared to 2004 demands. Approximately 31% of the available water volume will have its origin in wastewater reuse, and around 98% of all available water resources will be used. The total contamination load by 2030 was estimated to have increased up to approximately 39%. By 2054, the conditions will be more stressful, considering that water demand will have increased up to around 76%, as compared with the value in 2004, when approximately 39% of the available water volume will have its origin in wastewater reuse. The total demand for water resources will have risen to around 131% of the available volume. Meanwhile, the contamination load will have increased to up to approximately 91%, compared with 2004.

In Fig. 6, the 2004 Falkenmark Index for BaU scenario started at 1,403 m3 inhabitant1 year1 (713 inhab Mm3 year1) in RB-PCJ; by 2030 it will be 1,008 m3 inhab1 year1 (992 inhab Mm3 year1); and by 2054 it goes up to 734 m3 inhab1 year1 (1,363 inhab Mm3 year1). Water stress exists when the value is between 1,000 to 1,600 m3 inhab1 year1, and chronic water shortage occurs when the available water volume is between 500 and 1,000 m3 inhab1 year1. For values less than 500 m3 inhab1 year1, the water resources are beyond the barrier of management capacity (Falkenmark 1989). The other four scenarios studied also showed that RB-PCJ will be in a chronic water shortage situation.

Also, in Fig. 6, when the basin development was analyzed using Keller et al. (1998), by 2007, BH-PCH is at Phase II, stage 1: Conservation Phase. In other words, this is the stage where policies to reduce the water demand and to increase the efciency of water use should be taken. For the BaU scenario, by 2008, RB-PCJ will be entering Phase II, stage 2; which the nal stage of this phase. By 2016, RB-PCJ will be at the initial stage of Phase III: Augmentation Phase. This is the nal basin development

770 R.M. Snchez-Romn et al.

Fig. 6 Relationship between Total Water Demand and Water Availability, vertical axis, and Population Density per Unit of Flow, horizontal scale, for Piracicaba, Capivari and Jundia River Basins estimated using the Piracicaba, Capivari and Jundia River Basins Water Resources Model; for a 50-year time frame simulation with ve scenarios studied (Adapted by the authors from: Falkenmark et al. 2007; and Keller et al. 1998)

phase. It is the phase where water resources have to come from water transfers or by desalting water. The other scenario predictions are also not very encouraging.

Figure 7 shows the Sustainability Index (SI) as proposed by Xu et al. (2002) and estimated using WRM-PCJ. For the BaU scenario, the SI is 0.44 by 2004. It goes down to 0.33 by 2030, and to 0.20 by 2054. The WRM-PCJ considers the reuse of wastewater as part of the available water, a contrast to the result presented by the relation use-to-availability at the y-axis in Fig. 5. If the SI value is greater than 0.2, then the water offer is under low or no stress; if the SI value is smaller than 0.2, then

Fig. 7 Sustainability Index, proposed by Xu et al. (2002), for Piracicaba, Capivari and Jundia River Basins estimated using the Piracicaba, Capivari and Jundia River Basins Water Resources Model (WRM-PCJ)

Water Resources Assessment at Piracicaba, Capivari and Jundia 771

Table 2 Results of water use indexes from the ve scenarios simulated using Piracicaba, Capivari and Jundia River Basins Water Resources Model (WRM-PCJ)

Scenario Index 2004 2010 2020 2030 2040 2054

WU 74.41 83.95 96.04 97.80 110.37 131.29 1 SI 0.44 0.40 0.35 0.33 0.28 0.20

FI 1,403 1,302 1,147 1,008 884 734 WU 82.68 93.28 106.71 108.67 122.64 145.882 SI 0.40 0.36 0.30 0.28 0.23 0.15 FI 1,263 1,172 1,032 907 795 660 WU 93.02 104.94 120.05 122.26 137.97 164.113 SI 0.34 0.30 0.25 0.23 0.17 0.09 FI 1,123 1,042 917 806 707 587 WU 74.41 83.95 96.04 96.70 107.8 126.274 SI 0.44 0.40 0.35 0.34 0.29 0.23 FI 1,403 1,302 1,147 1,008 884 734 WU 74.41 92.44 104.53 106.29 118.86 139.785 SI 0.44 0.34 0.29 0.27 0.22 0.15 FI 1,403 1,302 1,147 1,008 884 734

WU Water Use (%), SI Sustainability Index (dimensionless), FI Falkenmark Index (m3 hab1 year1)

the water resources are vulnerable. SI values equal to zero indicate that the water offer is unsustainable.

The different methods to assess water resources and basin development at RBPCJ showed that appropriate and urgent decisions should be taken to stop the deterioration of available water resources. By 2030 the RB-PCJ water resources situation will be extremely demanding and stressful, as the estimated coefcients showed. Additionally, by 2054, the situation will be very close to unsustainable (Table 2). Therefore, it is necessary to immediately take appropriate steps to develop a water resources management policy to avoid ecological chaos in RB-PCJ.

4 Conclusions

It can be concluded:

1. The RB-PCJ is at phase II.1 according to Keller et al. (1998) characterization of watershed development;

2. Since the lions share is in the urban areas, it is necessary to establish a new policies to improve water saving practices by the population;

3. The model WRM-PCJ showed to be an excellent water resources management tool to be used by the watershed committee members, and it should be consider as one of its current water management decision tools and its use promoted among all committee members.

Acknowledgements The authors thank the Brazilian National Council of Scientic and Technological Development (CNPqProcesso 151864/2007-1), Fundao de Amparo Pesquisa do Estado de So Paulo (FAPESPProcesso 2006/60954-4) and the National Institute of Science and Technology in Irrigation Engineering (INCTEI) for nancial support.

772 R.M. Snchez-Romn et al.

References

Costa MPB (1993) Agroecologia: uma alternativa vivel s reas reformadas e produo familiar.Revista Reforma Agrria 23:5369

DAEE (2007) Departamento de guas e Energia Eltrica (State of So Paulos Department of

Water and Power). Available at: http://www.daee.sp.gov.br/

Web End =http://www.daee.sp.gov.br/ . Accessed 06 May 2007 Falkenmark M (1989) The massive water scarcity now threatening Africawhy isnt it being addressed? Ambio 18:112118Falkenmark M, Berntell A, Jgerskog A, Lundqvist J, Matz M, Tropp H (2007) On the verge of a new scarcity: call goes good governance and human ingenuity. IWI Policy Brief, Stockholm International Water Institute (SIWI), Stockholm, SwedenForrester JW (1961) Industrial dynamics. MIT Press, CambridgeForrester JW (1980) Information sources for modeling the national economy. J Am Stat Assoc

75:555574

Grcic B, Munitic A (2005) System dynamics approach to validation. Available at: http://www.efst.hr/~grcic/b2.html

Web End =http://www.efst. http://www.efst.hr/~grcic/b2.html

Web End =hr/ http://www.efst.hr/~grcic/b2.html

Web End =grcic/b2.html . Accessed 05 July 2006

IBGE (2007) Instituto Brasileiro de Geograa e Estatstica (Brazilian Institute of Geography and

Statistics). Available at: http://www.ibge.gov.br/home/

Web End =http://www.ibge.gov.br/home/ . Accessed 30 May 2007IEA (2007) Instituto de Economia Agrcola (Agricultural Economics Institute). Available at: http://www.iea.sp.gov.br/

Web End =http:// http://www.iea.sp.gov.br/

Web End =www.iea.sp.gov.br/ . Accessed 14 May 2007INMET (2007) Instituto Nacional de Meteorologia (Weather National Institute). Available at: http://www.inmet.gov.br/

Web End =http:// http://www.inmet.gov.br/

Web End =www.inmet.gov.br/ . Accessed 12 May 2007INPE (2007) Instituto Nacional de Pesquisas Espaciais (National Institute for Space Research).

Available at: http://www.inpe.br/

Web End =http://www.inpe.br/ . Accessed 22 May 2007

IPEA (2007) Instituto de Pesquisa Econmica Aplicada (Applied Economic Research Institute).Available at: http://www.ipea.gov.br/

Web End =http://www.ipea.gov.br/ . Accessed 28 May 2007

IRRIGART (2004) Relatrio nal. Relatrio da situao dos recursos hdricos das Bacias Hidrogrcas dos Rios Piracicaba, Capivari e Jundia2002/2003, vol II. Comit das Bacias Hidrogrcas dos Rios Piracicaba, Capivari e JundiaITHINK ANALYST (1997) An introduction to systems thinking. High Performance Systems, Inc Keller J, Keller A, Davids G (1998) River basin development phases and implications of closure.

J Appl Irrig Sci 33:145163

Ohlsson L, Turton AR (1999) The turning of screw. Social resource scarcity the bottle-neck in adaptation to water scarcity. Water Issues Study Group, School of Oriental and African Studies (SOAS Occasional Paper No. 19). University of London, LondonPerez Maqueo O, Delfn C, Fregoso A, Cotler H (2006) Modelos de simulacin para la elaboracin y evaluacin de los programas de servicios ambientales hdricos. Gaceta Ecolgica 78:6584 PLANO ESTADUAL DOS RECURSOS HIDRICOS 20042007 DO ESTADO DE SO PAULO

(PERH: State of So Paulos Water Resources State Plan for 20042007) (2004) Sumario executivo. Consrcio JMR EngecorpsPLANO ESTADUAL DOS RECURSOS HIDRICOS 20042007 DO ESTADO DE SO PAULO

(PERH: State of So Paulos Water Resources State Plan for 20042007) (2005) Relatrio sntese do plano. Consrcio JMR EngecorpsPOWERSIM Co (1996) Introduction to system dynamics. Powersim, RestonRaskin P, Gleick P, Kirshen P, Pontius G, Strzepek K (1997) Water futures: assessment of long-range patterns and prospects. Stockholm Environment Institute, Stockholm

RELATRIO 0 (1999) Situao dos recursos hdricos das Bacias Hidrogrcas dos Rios Piracicaba,

Capivari e Jundia. UGRHI 5. Relatrio tcnico nal1o volume. CETEC/CBH-PCJRuth M, Hannon B (1994) Modeling dynamic economic systems. Springer, New YorkRykiel EJ (1996) Testing ecological models. The meaning of validation. Ecol Model 90:229244 SABESP (2007). Secretaria de Agricultura e Abastecimento do Estado de So Paulo (State of

So Paulos Agriculture and Supply Secretary). Available at: http://www.agricultura.sp.gov.br/

Web End =http://www.agricultura.sp.gov.br/ . Accessed 03 May 2007Snchez-Romn RM, Folegatti MV, Orellana-Gonzlez AMG (2008) Water resources assessment at

Piracicaba, Capivari and Jundiai River Basin: a dynamic systems approach. In 21st century watershed technology: improving water quality and environment conference proceedings. ASABE, St. Joseph, MI, USASantos M (1982) O espao e os seus elementos: questes de mtodo. Rev Geogr Ens 1:1930

Water Resources Assessment at Piracicaba, Capivari and Jundia 773

SIRGH (2007) Sistema de informaes para o gerenciamento de recursos hdricos do estado de So

Paulo (State of So Paulos Water Resources Management Information System). Available at: http://www.sigrh.sp.gov.br/cgi-bin/bdhm.exe/plu

Web End =http://www.sigrh.sp.gov.br/cgi-bin/bdhm.exe/plu . Accessed 25 April 2007Souchon Y, Keith P (2001) Freshwater sh habitat: science, management and conservation in France.

Aquatic Ecosystem Health and Management Society 4:401412Sterman JD (2005) Systems dynamics modeling for project management. Available at: http://www.systemdynamics.org

Web End =http://www. http://www.systemdynamics.org

Web End =systemdynamics.org . Accessed 18 August 2006Turton AR (1999) Water scarcity and social adaptive capacity: towards an understanding of the social dynamics of water demand management in developing countries. Water Issues Study Group, School of Oriental and African Studies (SOAS Occasional Paper No. 9). University of London, LondonUNICA (2007) Unio da indstria de cana-de-acar (Sugarcane Industry Union). Available at: http://www.portalunica.com.br

Web End =http://www.portalunica.com.br . Accessed 12 May 2007Wiazowski BA, Silva CAB, Lourenzani WL (1999) O uso de sistemas dinmicos como ferramenta de aprendizagem. Eco Rural 3:2933Xu ZX, Takeuchi K, Ishidara H, Zhang XW (2002) Sustainability analysis for yellow river water resources using the system dynamics approach. Water Resour Manag 16:239261