Quiz & test questions Grade 10 Science
Ashcombe River Basin: A Water Cycle and Earth Systems Quiz
A grade 10 science quiz mixing multiple-choice, short-answer, and computation items on residence time, water distribution, and Earth-system feedbacks.
Objectives
- Students will define residence time and compare it across parts of the water cycle.
- Students will calculate residence time and convert reservoir storage to gallons.
- Students will explain feedbacks that link a river change to other Earth systems.
Vocabulary
- Residence time
- Residence time is how long a drop of water typically stays in one part of the water cycle before moving on. Water passes through the air quickly but can stay underground for a very long time.
- Reservoir
- A human-made lake, usually created by a dam, that stores water for later. Reservoirs supply cities and farms and help control floods.
- Watershed
- A watershed is all the land where rain that falls will drain to the same stream, river, or lake. Everyone lives in a watershed, no matter how far from the water they live.
Also: feedback, sediment
Teacher overview
This 30-minute quiz is worth 24 points and checks whether students can reason about the water cycle and Earth-system feedbacks. It mixes three multiple-choice items, three short-answer items, and three computation items, all set in the fictional Ashcombe River Basin. The storage and outflow figures are invented for this scenario, while the distribution and residence-time facts are standard values.
Assessment
Suppose the fictional Ashcombe River Basin is the setting for every item. Answer each item and show your work on the computation problems.
- (2 points) About what share of Earth's water is accessible fresh water in liquid form?
- A) about 97 percent
- B) about 70 percent
- C) about 2 percent
- D) less than 1 percent
- (2 points) On average, water spends about 9 days in which part of the water cycle?
- A) deep groundwater
- B) the atmosphere
- C) glaciers and ice caps
- D) the deep ocean
- (3 points) Define "residence time" and explain why water in deep groundwater has a much longer residence time than water in the atmosphere.
- (3 points) The Ashcombe reservoir holds 900 acre-feet of water and releases an average of 30 acre-feet per day. Calculate the reservoir's residence time in days, using residence time equals storage divided by outflow.
- (3 points) A pond in the basin holds 5 acre-feet. Using the conversion that one acre-foot equals 325,851 gallons, calculate the pond's volume in gallons.
- (2 points) Building a dam on the Ashcombe River can create feedbacks in other Earth systems. Which pairing is a documented effect of a dam?
- A) increases groundwater recharge upstream and increases coastal erosion downstream
- B) lowers groundwater recharge and adds sediment to the coast
- C) has no effect on groundwater or the coast
- D) raises the ocean's salinity worldwide
- (3 points) Explain the feedback in item 6: why does trapping sediment behind a dam lead to more erosion at the coast where the river meets the sea?
- (3 points) A wetland in the basin is drained for development. Using the idea of Earth-system feedbacks, predict one effect on local humidity or on runoff, and explain it.
- (3 points) Atmospheric water has an average residence time of about 9 days. About how many times does atmospheric water cycle through in a 365-day year? Show your calculation and round to the nearest whole number.
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Answer Key
- Answer: D) less than 1 percent. Most of Earth's water is in the oceans, and only a small fraction is accessible liquid fresh water available for use.
- Answer: B) the atmosphere. Water stays in the atmosphere about 9 days on average, far less time than it spends in deep groundwater.
- Answer: Residence time is the average length of time a water molecule stays in a given reservoir before it moves on. Deep groundwater moves very slowly through rock and sediment, so its residence time can reach centuries, while atmospheric water cycles out in days because evaporation and precipitation move it quickly.
- Answer: 30 days. Residence time = storage / outflow = 900 acre-feet / 30 acre-feet per day = 30 days.
- Answer: 1,629,255 gallons. 5 acre-feet x 325,851 gallons per acre-foot = 1,629,255 gallons.
- Answer: A) increases groundwater recharge upstream and increases coastal erosion downstream. A dam holds water back, which raises recharge upstream, and it traps sediment, which starves the coast and increases erosion downstream.
- Answer: A river normally carries sediment to its mouth, where that sediment rebuilds beaches and deltas. A dam traps the sediment in its reservoir, so less reaches the coast. With its supply of new sediment cut off, the coast is worn away by waves faster than it is replaced, so erosion increases.
- Answer: Accept either effect with a sound explanation. For example, draining the wetland removes a large area of standing water and wet soil that added moisture to the air, so local humidity would drop. Or, because the wetland no longer soaks up and holds rainfall, more water would run off quickly, increasing runoff and flood risk downstream.
- Answer: About 41 times. 365 days / 9 days per cycle = 40.6, which rounds to about 41 times per year.
Differentiation
Support
Provide the residence-time formula (storage divided by outflow) and the acre-foot-to-gallon conversion on a reference strip, and allow a calculator on every computation item. Offer a word bank for the short-answer items.
Extension
Ask students to explain how the reservoir's residence time from item 4 would change if a drought cut the outflow in half, and to describe one water-quality effect of water sitting in the reservoir longer.
ELL supports
Pre-teach "residence time," "reservoir," "sediment," and "feedback" with simple labeled visuals in English and, where possible, students' home languages. Provide sentence frames for the short-answer items, such as "Draining the wetland would ___ because ___."