Question: How many children work year round in the continent where the river the Tekeze river turns into is located?

full_context: Document 1: Child labour: Systematic use of child labour was common place in the colonies of European powers between 1650 and 1950. In Africa, colonial administrators encouraged traditional kin-ordered modes of production, that is hiring a household for work not just the adults. Millions of children worked in colonial agricultural plantations, mines and domestic service industries. Sophisticated schemes were promulgated where children in these colonies between the ages of 5–14 were hired as an apprentice without pay in exchange for learning a craft. A system of Pauper Apprenticeship came into practice in the 19th century where the colonial master neither needed the native parents' nor child's approval to assign a child to labour, away from parents, at a distant farm owned by a different colonial master. Other schemes included 'earn-and-learn' programs where children would work and thereby learn. Britain for example passed a law, the so-called Masters and Servants Act of 1899, followed by Tax and Pass Law, to encourage child labour in colonies particularly in Africa. These laws offered the native people the legal ownership to some of the native land in exchange for making labour of wife and children available to colonial government's needs such as in farms and as picannins.
Document 2: Tekezé River: The Tekezé River rises in the central Ethiopian Highlands near Mount Qachen within Lasta, from where it flows west, north, then west again, forming the westernmost border of Ethiopia and Eritrea from the confluence of the Tomsa with the Tekezé at to the tripoint between the two countries and Sudan at . After entering northeastern Sudan at the tripoint it joins the Atbarah River, which is a tributary of the Nile. The Tekezé is perhaps the true upper course of the Atbarah, as the former follows the longer course prior to the confluence of the two rivers.
Document 3: Sahara: The desert comprises much of North Africa, excluding the fertile region on the Mediterranean Sea coast, the Atlas Mountains of the Maghreb, and the Nile Valley in Egypt and Sudan. It stretches from the Red Sea in the east and the Mediterranean in the north to the Atlantic Ocean in the west, where the landscape gradually changes from desert to coastal plains. To the south, it is bounded by the Sahel, a belt of semi-arid tropical savanna around the Niger River valley and the Sudan Region of Sub-Saharan Africa.
Document 4: Walaqa River: The Walaqa River, a tributary of the Blue Nile, is river in the Amhara Region of Ethiopia. Wegde is located to its north. Mida Woremo and Dera are to the south, while Kelala is to the northeast. The Walaqa River may have been the northern boundary of the historical province of Walaqa.
Document 5: Child labour: Other legal factors that have been implemented to end and reduce child labour includes the global response that came into force in 1979 by the declaration of the International Year of the Child. Along with the Human Rights Committee of the United Nations, these two declarations worked on many levels to eliminate child labour. Although many actions have been taken to end this epidemic, child labour in Africa is still an issue today due to the unclear definition of adolescence and how much time is needed for children to engage in activities that are crucial for their development. Another issue that often comes into play is the link between what constitutes as child labour within the household due to the cultural acceptance of children helping run the family business. In the end, there is a consistent challenge for the national government to strengthen its grip politically on child labour, and to increase education and awareness on the issue of children working below the legal age limit. With children playing an important role in the African economy, child labour still plays an important role for many in the 20th century.
Document 6: Yangtze: The river originates from several tributaries in the eastern part of the Tibetan Plateau, two of which are commonly referred to as the ``source ''. Traditionally, the Chinese government has recognized the source as the Tuotuo tributary at the base of a glacier lying on the west of Geladandong Mountain in the Tanggula Mountains. This source is found at 33 ° 25 ′ 44'' N 91 ° 10 ′ 57 ''E ﻿ / ﻿ 33.42889 ° N 91.18250 ° E ﻿ / 33.42889; 91.18250 and while not the furthest source of the Yangtze, it is the highest source at 5,342 m (17,526 ft) above sea level. The true source of the Yangtze, hydrologically the longest river distance from the sea, is at Jari Hill at the head of the Dam Qu tributary, approximately 325 km (202 mi) southeast of Geladandong. This source was only discovered in the late 20th century and lies in wetlands at 32 ° 36 ′ 14'' N 94 ° 30 ′ 44 ''E ﻿ / ﻿ 32.60389 ° N 94.51222 ° E ﻿ / 32.60389; 94.51222 and 5,170 m (16,960 ft) above sea level just southeast of Chadan Township in Zadoi County, Yushu Prefecture, Qinghai. As the historical spiritual source of the Yangtze, the Geladandong source is still commonly referred to as the source of the Yangtze since the discovery of the Jari Hill source.
Document 7: Child labour: In developing countries, with high poverty and poor schooling opportunities, child labour is still prevalent. In 2010, sub-saharan Africa had the highest incidence rates of child labour, with several African nations witnessing over 50 percent of children aged 5–14 working. Worldwide agriculture is the largest employer of child labour. Vast majority of child labour is found in rural settings and informal urban economy; children are predominantly employed by their parents, rather than factories. Poverty and lack of schools are considered as the primary cause of child labour.
Document 8: Birbir River: The Birbir River of southwestern Ethiopia is a tributary of the Baro River, which it creates when it joins the Gebba at latitude and longitude . It is politically important because its course defines part of the boundary between the Mirab Welega and Illubabor Zones of the Oromia Region.
Document 9: Flooding of the Nile: The flooding of the Nile is the result of the yearly monsoon between May and August causing enormous precipitations on the Ethiopian Highlands whose summits reach heights of up to 4550 m (14,928 ft). Most of this rainwater is taken by the Blue Nile and by the Atbarah River into the Nile, a less important amount is flowing through the Sobat and the White Nile into the Nile. During this short period, those rivers contribute up to ninety percent of the water of the Nile and most of the sedimentation carried by it, but after the rainy season, dwindle to minor rivers.
Document 10: Child labour: Children working at a young age has been a consistent theme throughout Africa. Many children began first working in the home to help their parents run the family farm. Children in Africa today are often forced into exploitative labour due to family debt and other financial factors, leading to ongoing poverty. Other types of domestic child labour include working in commercial plantations, begging, and other sales such as boot shining. In total, there is an estimated five million children who are currently working in the field of agriculture which steadily increases during the time of harvest. Along with 30 percent of children who are picking coffee, there are an estimated 25,000 school age children who work year round.
Document 11: Atbarah River: The Atbarah River (; transliterated: Nahr 'Atbarah) in northeast Africa rises in northwest Ethiopia, approximately 50 km north of Lake Tana and 30 km west of Gondar. It flows about 805 km (500 mi) to the Nile in north-central Sudan, joining it at the city of Atbarah (). The river's tributary, the Tekezé (Setit) River, is perhaps the true upper course of the Atbarah, as the Tekezé follows the longer course prior to the confluence of the two rivers (at 14° 10' N, 36° E) in northeastern Sudan. The Atbarah is the last tributary of the Nile before it reaches the Mediterranean.
Document 12: Medjerda River: The Medjerda River (), the classical Bagrada, is a river in North Africa flowing from northeast Algeria through Tunisia before emptying into the Gulf of Tunis and Lake of Tunis. With a length of , it is the longest river of Tunisia. It is also known as the Wadi Majardah or Mejerha ().
Document 13: Nile: The Nile (Arabic: النيل‎, written as al-Nīl; pronounced as an-Nīl) is a major north-flowing river in northeastern Africa, and is the longest river in Africa and the disputed longest river in the world (Brazilian government claims that the Amazon River is longer than the Nile). The Nile, which is about 6,650 km (4,130 mi) long, is an "international" river as its drainage basin covers eleven countries, namely, Tanzania, Uganda, Rwanda, Burundi, the Democratic Republic of the Congo, Kenya, Ethiopia, Eritrea, South Sudan, Republic of the Sudan and Egypt. In particular, the Nile is the primary water source of Egypt and Sudan.The river Nile has two major tributaries, the White Nile and Blue Nile. The White Nile is considered to be the headwaters and primary stream of the Nile itself. The Blue Nile, however, is the source of most of the water and silt. The White Nile is longer and rises in the Great Lakes region of central Africa, with the most distant source still undetermined but located in either Rwanda or Burundi. It flows north through Tanzania, Lake Victoria, Uganda and South Sudan.  The Blue Nile begins at Lake Tana in Ethiopia and flows into Sudan from the southeast. The two rivers meet just north of the Sudanese capital of Khartoum.The northern section of the river flows north almost entirely through the Sudanese desert to Egypt, then ends in a large delta and flows into the Mediterranean Sea. Egyptian civilization and Sudanese kingdoms have depended on the river since ancient times. Most of the population and cities of Egypt lie along those parts of the Nile valley north of Aswan, and nearly all the cultural and historical sites of Ancient Egypt are found along river banks.
Document 14: Sobat River: The Sobat River is a river of the Greater Upper Nile region in northeastern South Sudan, Africa. It is the most southerly of the great eastern tributaries of the White Nile, before the confluence with the Blue Nile.
Document 15: Child labour: Small-scale artisanal mining of gold is another source of dangerous child labour in poor rural areas in certain parts of the world. This form of mining uses labour-intensive and low-tech methods. It is informal sector of the economy. Human Rights Watch group estimates that about 12 percent of global gold production comes from artisanal mines. In west Africa, in countries such as Mali - the third largest exporter of gold in Africa - between 20,000 and 40,000 children work in artisanal mining. Locally known as orpaillage, children as young as 6 years old work with their families. These children and families suffer chronic exposure to toxic chemicals including mercury, and do hazardous work such as digging shafts and working underground, pulling up, carrying and crushing the ore. The poor work practices harm the long term health of children, as well as release hundreds of tons of mercury every year into local rivers, ground water and lakes. Gold is important to the economy of Mali and Ghana. For Mali, it is the second largest earner of its export revenue. For many poor families with children, it is the primary and sometimes the only source of income.
ground_truth: estimated 25,000
sub_queries: What river does Tekezé River turn into? Answer: Atbarah River
Atbarah River >> continent Answer: Africa
How many children work year round in Africa ? Answer: estimated 25,000