Drought and Water Cruises: Science, Technology, and Management Issues - Chapter 14 potx

367 14 Droughts and Water Stress Situations in Spain MANUEL MENÉNDEZ PRIETO CONTENTS I. Main Characteristics of Droughts in Spain 368 A. Introduction: Water Management and Planning Framework in Spain 368 B. Drought Definition 369 C. The Experience of the 1990–95 Drought 371 II. Driving Forces and Pressures in Water Stress Situations 373 A. Water Balance in Spain 373 B. Potential Effects of Global Warming 376 C. Trends in Water Demands 377 III. Response Strategies 378 A. Early Identification of Droughts 378 B. Systems Operation 380 IV. Conclusions and Recommendations 383 References 384 DK2949_book.fm Page 367 Friday, February 11, 2005 11:25 AM Copyright 2005 by Taylor & Francis Group 368 Prieto I. MAIN CHARACTERISTICS OF DROUGHTS IN SPAIN A. Introduction: Water Management and Planning Framework in Spain In Spain, water is not just another natural resource. Drought is more than a combination of meteorological factors because it usually produces conflicts between users, deterioration in river ecology, and increased public awareness. During drought, the decreased availability of water results in greater pressure on existing surface and subsurface water supplies, and debates about potential remediation measures usually go beyond the scientific or technical spheres and into the political sphere. Water management in Spain is based on river basin departments (RBDs) (see location of main Spanish river basins in Figure 1). If water runs through more than one regional territory (autonomous community), the RBD depends on the state administration and is called an inter-community Figure 1 Location of main river basin departments (black border lines) and autonomous communities (shaded regions). 100 0 100 120 km N DK2949_book.fm Page 368 Friday, February 11, 2005 11:25 AM Copyright 2005 by Taylor & Francis Group Droughts and Water Stress Situations in Spain 369 basin . An intra-community basin lies completely within the limits of one autonomous community, and the regional admin- istration assumes authority for water management. Water planning is accomplished through two main instruments: basin hydrological plans and the national hydro- logical plan. The Water Act of 1985 conceived the basin hydrological plans as the central instruments in regulating water, to which, according to the text of the act, “all action in the public domain is subject.” After a drafting process of more than 10 years, the legal texts of the plans were finally approved in 1998. Afterward, information about water resources in Spain was collected, analyzed, and described in the so-called “Libro Blanco del Agua en España” (“White Paper on Water in Spain”) (Ministerio de Medio Ambiente, 2000), and it was used as the basis of the national hydrological plan. Approved by the Spanish Parliament in July 2001 and partially modified in 2004, the national hydrological plan includes the following measures to ensure the coordination of the different basin hydrological plans: forecasts, structural measures, and mod- ifications affecting existing public supply or irrigation sys- tems. B. Drought Definition As in other Mediterranean countries with large arid or semi- arid areas, droughts in Spain are difficult to evaluate and quantify and thus are difficult to define. Many definitions are used, and often it is not clear when a drought situation has started or finished or even if it has existed. In some large river basins, the definition of a drought is based on simple rainfall statistics. For example, for the river Ebro, one of the largest rivers in Spain, a dry period starts according to Spanish law, “when rainfall amounts in two consecutive months within the series are lower than 60% of the average rainfalls for these months.” For the river Guadiana, “a situation of drought occurs when the sum of rainfalls registered during the 12 preceding months is lower than those registered in 75% of the cases within the period analyzed.” In some cases, the definition of drought is based on the relationship between supply and DK2949_book.fm Page 369 Friday, February 11, 2005 11:25 AM Copyright 2005 by Taylor & Francis Group 370 Prieto demand. For instance, in the Guadalquivir River basin, the following definition is used: “a situation in which the resources accumulated are insufficient to satisfy the demand.” In the river basin Norte III * (one of the wettest in Spain), the experi- ence of previous droughts must be taken into account to plan water supply facilities. The Norte III hydrological plan points out “the works have to be planned in accordance with the demand on the basis of the droughts that occurred in the 1941–43 and 1989–90 periods, without admitting any errors and considering that there are sufficient resources for such purposes within the scope of the plan.” This plan also defines “dry year” as one in which the yearly cumulative flow is half of the average and “very dry year” as one in which the cumu- lative flow amounts to 75% of the flow registered in a dry year, or slightly more than 35% of the yearly average cumulative flow. Regarding drought definition, an interesting case refers to the provisions about emergency situations included in the treaty between Spain and Portugal on transboundary river basins. This agreement, known as Albufeira, was signed in Albufeira, Portugal, at the end of 1998. It establishes that in case of drought situations, Spain will not be in breach of the treaty for failing to maintain the quantity or quality of the discharges fixed in the agreement as minimum inflow to Por- tugal for standard meteorological conditions. In a drought situation, it is understood that the first priority should be to maintain the water supply for urban uses and, in conse- quence, other requirements of the treaty would be temporarily repealed. Drought situations are defined on the basis of a referenced precipitation calculated for a specific time period in each river basin using data from only two or three rain gauges through different weights that are applied at each control point. This precipitation is compared with a percentile of the mean for the same period. Tables 1 and 2 explain the drought definition process proposed for the river Miño. * Norte river basin is divided into three subbasins for administrative pur- poses: Norte I, Norte II, and Norte III. DK2949_book.fm Page 370 Friday, February 11, 2005 11:25 AM Copyright 2005 by Taylor & Francis Group Droughts and Water Stress Situations in Spain 371 The lack of a universally accepted definition for drought has consequences that go beyond academic discussions. For example, as will be indicated in the following section, Spanish water regulations allow river authorities to adopt emergency measures, including occupation of private lands or stopping specific uses such as irrigation, if a drought situation has been declared. C. The Experience of the 1990–95 Drought The most severe droughts in Spain in the last century occurred in 1941–45, 1979–83, and 1990–95. These three T ABLE 1 Step 1: Calculation of the Mean ( M ) a and Reference ( R ) Precipitation River Basin Rain Gauge Stations Weights of Each Control Point for the Precipitation Assessment Miño Lugo Orense Ponferrada 30% 47% 23% a Calculated for the period 1945–46 to 1996–97 and updated every 5 years. T ABLE 2 Step 2: Identification of a Drought Situation River Basin Control Point (along border between Spain and Portugal) Minimum Discharge to Be Ensured by Spain along the Border with Portugal (millions m 3 /year) Starting Date for Derogation Period is July 1 if … Ending Date for Derogation Period is the Following Month to December if … Miño Salto de Freira 3700 R ( cumulative rainfall from October 1 to July 1) <70% M (cumulative rainfall from October 1 to July 1) R (cumulative rainfall from October 1 to July 1) > M (cumulative rainfall from October 1 to July 1) DK2949_book.fm Page 371 Friday, February 11, 2005 11:25 AM Copyright 2005 by Taylor & Francis Group 372 Prieto droughts were extensive and affected most of the country. The map in Figure 2 shows the percentage decrease in average rainfall from October 1990 to September 1995 compared to the average rainfall for the 1940–1996 period. Several river basins suffered decreased rainfall percentages, around 30%. The resulting reduction in runoff in most of the country was more than 40% and amounted to more than 70% in two basins (Guadiana and Guadalquivir). The drought of 1990–1995 affected more than one-third of the total population of Spain. For example, during these years, there were severe restrictions on water use in cities like Granada, Malaga, and Seville, and irrigation was banned during 1993–95 in the Guadalquivir River basin. The situa- tion forced cities and regions to adopt different measures. For example, the search for new groundwater resources was car- Figure 2 Percentage decrease in rainfall during 1990–1995 in Spain in comparison with the average values for the period 1940–1996. 100 0 N 100 120 >40% <0% 0% 1–10% 11–20% 21–30% 31–40% km DK2949_book.fm Page 372 Friday, February 11, 2005 11:25 AM Copyright 2005 by Taylor & Francis Group Droughts and Water Stress Situations in Spain 373 ried out on a large scale. The city of Granada, with a popu- lation of 300,000 and a yearly demand of around 35 million m 3 , had to be supplied mainly with groundwater, changing its water supply system, which had previously used mainly sur- face water. Groundwater was also used to solve problems in irrigated areas such as the Jucar and Segura River basins. Unconventional methods were applied, such as increasing water reuse and even transporting water by boat to cities like Cadiz and Majorca. New desalinization plans were proposed, but most were never carried out. Regulations were adopted to allow emergency measures to be taken. For example, the so-called Commissions on Droughts in each RBD had the power to reduce or suspend water use and require users to install specific devices for saving water. A decree issued by the Council of Ministers empowered the government, after consulting the Commissions on Droughts, to adopt “such mea- sures as shall be necessary as regards the utilization of the public water domain, even if a concession has been granted for its exploitation,” if an extraordinary drought occurs. II. DRIVING FORCES AND PRESSURES IN WATER STRESS SITUATIONS A. Water Balance in Spain Spain on average has sufficient water to meet water demands, but these resources are very unevenly distributed. According to the “White Paper on Water in Spain” (Ministerio de Medio Ambiente, 2000), natural water resources are estimated at 111 billion m 3 per year, distributed as shown in Figure 3. The total amount of natural water resources is not avail- able for abstractions. * Two limitations are usually considered: (1) a precautionary reserve of 20% of the natural resources for environmental requirements, and (2) the minimum water volume that must be maintained along the Spanish–Portu- guese border, per the Albufeira Treaty. Annual freshwater abstraction by sector is shown in Table 3 (Ministerio de Medio Ambiente, 2000). To illustrate the possibilities of reusing water, we obtain the consumptive DK2949_book.fm Page 373 Friday, February 11, 2005 11:25 AM Copyright 2005 by Taylor & Francis Group 374 Prieto fraction of the water demand that cannot be reused, by apply- ing different percentages: 20% for urban use, 80% for irriga- tion, 20% for industrial use, and 5% for energy use. With the percentages for reusing water and data obtained from the basin hydrological plans, the distribution of the total water demand in Spain is shown in Figure 4. Once maps of potential water resource supply and demand have been drawn up, they can be compared to identify existing imbalance and its territorial location (see Figure 5). * EUROSTAT (Statistical Office of the European Communities) defines water abstraction as “water removed from any source, either permanently or temporarily.” In Europe, water abstraction is equivalent to water with- drawal. Water demand is defined as the “volume of water requested by users to satisfy their needs.” According to EUROSTAT, water use is “water actually used by end users for a specific purpose within a territory, such as for domestic use, irrigation or industrial processing.” Figure 3 Natural annual water resources in Spain (mm). (From Ministerio de Medio Ambiente, 2000.) 100 0 100 120 >800 1–50 51–100 201–300 101–200 301–400 401–500 501–600 601–700 701–800 km DK2949_book.fm Page 374 Friday, February 11, 2005 11:25 AM Copyright 2005 by Taylor & Francis Group Droughts and Water Stress Situations in Spain 375 T ABLE 3 Annual Freshwater Abstraction in Spain, by Sector Urban Water Demand Consumptive Urban Water Demand Agricultural Water Demand (Irrigation) Consumptive Agricultural Water Demand (Irrigation) Industry Water Demand* 5,393 1,079 27,863 22,290 1,920 Consumptive Industrial Water Demand Energy Water Demand Consumptive Energy Water Demand Total Water Demand Total Consumptive Water Demand Returned Water 384 5,679 284 40,855 24,037 16,818 Note: All figures are in millions of cubic meters per year. Source : Ministerio de Medio Ambiente (2000). Figure 4 Total water demand in Spain (mm). (From Ministerio de Medio Ambiente, 2000.) 0 1–250 250–500 500–750 750–1000 1000–1250 1250–1500 1500–1750 1750–2000 2000–2250 2250–2500 2500–2750 2750–3000 3000–3200 3200–3500 >3500 DK2949_book.fm Page 375 Friday, February 11, 2005 11:25 AM Copyright 2005 by Taylor & Francis Group 376 Prieto B. Potential Effects of Global Warming Global warming effects on water resources availability could aggravate the situation described above, further upsetting the equilibrium between water supply and demand in some places. In Spain, according to the studies carried out by the Intergovernmental Panel on Climate Change, a doubling of CO 2 could cause a global annual temperature increase rang- ing from 1 to 4ºC by 2030. This would be accompanied by a decline of 5–15% in the global annual precipitation for the Mediterranean basin. The effects resulting from climate change on the availability of water resources have been eval- uated in the “White Paper on Water in Spain” under two scenarios. An optimistic scenario, Scenario 1, indicates an increase of 1ºC in the mean annual temperature. Scenario 2, a more pessimistic scenario, indicates a decline of 5% in the average annual precipitation and an increase of 1ºC in tem- Figure 5 Territorial distribution of water deficits (mm). (From Ministerio de Medio Ambiente, 2000.) 2600–2800 >2800 2400–2600 2200–2400 2000–2200 1800–2000 1600–1800 1400–1600 1200–1400 1000–1200 800–1000 600–800 400–600 200–400 1–200 0 DK2949_book.fm Page 376 Friday, February 11, 2005 11:25 AM Copyright 2005 by Taylor & Francis Group [...]... in the demand Higher water demands introduce new uncertainty factors and make some areas particularly vulnerable to drought situations In many places, overexploitation of resources exacerbates drought impacts As in other Mediterranean countries, many areas of Spain do not have adequate water resources to meet all demands In case of water conflicts in Spain, the Water Act of 1995 describes a water use... is outdated and results in significant leakage Figure 6 shows the expected trend of water demand in Spain, by sector Water demands are expected to change in small percentages in the future Urban water supply is an illustrative example Although the population will increase over the next few years, improved water use efficiency and water- saving practices produce only a slight decrease in demand as a final... AM Droughts and Water Stress Situations in Spain 377 perature Scenario 1 produces a decline of about 5% in water resources for the entire territory of Spain, with reductions around 10% in rivers such as Guadiana, Júcar, and Segura Scenario 2 causes a decrease of about 15% in the total water resources, with reductions of about 20% in the three rivers mentioned above C Trends in Water Demands Lack of water. .. of the product via prices), and the establishment of environmental protection measures: prevention of diffuse pollution, afforestation of arable lands, etc The second-highest consumptive water demand in Spain is urban water supply, currently at about 5 billion m3, which could be satisfied by available water resources However, the supply system is not always reliable Recent droughts in Spain, especially... operational at present A major increase in water demands in Spain is not foreseen because improved water use efficiency neutralizes the effect of population or irrigation growth However, the effects of global warming on water resources availability could break the equilibrium between water supply and demands Moreover, although Spain on average has sufficient water to meet Copyright 2005 by Taylor & Francis... Developing technical guidance for water management in drought situations Drought action plans should have clearly established rules and procedures, including criteria for applying restrictions, conditions for adopting special procedures to increase the flexibility and exchange of rights between users and their financial regulation, mobilization of hydrologic reserve areas, and temporary increases in the... indicators integrate supply and demand Copyright 2005 by Taylor & Francis Group DK2949_book.fm Page 383 Friday, February 11, 2005 11:25 AM 383 600 500 Phase 0 400 Phase 1 300 Phase 2 200 Phase 3 100 Sep Aug Jul Jun May Apr Mar Feb Jan Dec Nov 0 Oct Total Reservoir Storage (millions of m3) Droughts and Water Stress Situations in Spain Figure 8 Water stress situation phases for the water supply company in... protection measures Water consumption should be reduced to 80 liters per capita per day IV CONCLUSIONS AND RECOMMENDATIONS Spain, like many other Mediterranean countries, has not had clear criteria and strategies to identify and manage droughts In the severe drought of 1990–95 the crisis situation was identified too late, affecting the efficiency of emergency measures In addition, drought forecasting... available (precipitation, water stocks in reservoirs, or aquifer water table levels, for example) to alert people of the possible start date of a drought or to identify its intensity This approach has been adopted in the national hydrological plan of Spain Title II (Complementary Rules for Planning) and article 27 (Drought Management) of the plan note: The Environment Department and river basins affecting... Group DK2949_book.fm Page 384 Friday, February 11, 2005 11:25 AM 384 Prieto demands, its uneven distribution in time and space produces local and temporal water stress situations Response strategies are being developed and should be implemented in the near future They include: • Elaborating clear and consistent criteria for early drought identification, which would allow timely activation of established . Water Demand (Irrigation) Consumptive Agricultural Water Demand (Irrigation) Industry Water Demand* 5,393 1,079 27,863 22,290 1,920 Consumptive Industrial Water Demand Energy Water. Group Droughts and Water Stress Situations in Spain 375 T ABLE 3 Annual Freshwater Abstraction in Spain, by Sector Urban Water Demand Consumptive Urban Water Demand Agricultural. 367 14 Droughts and Water Stress Situations in Spain MANUEL MENÉNDEZ PRIETO CONTENTS I. Main Characteristics of Droughts in Spain 368 A. Introduction: Water Management and Planning